Superficial infections of skin and mucosal membranes by Candida causing local inflammation and discomfort are however common in many human populations.While clearly attributable to the presence of the opportunistic pathogens of the genus Candida, candidiasis describes a number of different disease syndromes that often differ in their causes and outcomes. Commonly referred to as a yeast infection, it is also technically known as candidosis, moniliasis, and oidiomycosis.

Classification

Candidiasis may be divided into the following types:

• Oral candidiasis (Thrush)
• Perlèche (Angular cheilitis)
• Candidal vulvovaginitis
• Candidal intertrigo
• Diaper candidiasis
• Congenital cutaneous candidiasis
• Perianal candidiasis
• Candidal paronychia
• Erosio interdigitalis blastomycetica
• Chronic mucocutaneous candidiasis
• Systemic candidiasis
• Candidid
• Antibiotic candidiasis (Iatrogenic candidiasis)

Signs and symptoms

Most candidial infections are treatable and result in minimal complications such as redness, itching and discomfort, though complication may be severe or fatal if left untreated in certain populations. In immunocompetent persons, candidiasis is usually a very localized infection of the skin or mucosal membranes, including the oral cavity (thrush), the pharynx or esophagus, the gastrointestinal tract, the urinary bladder, or the genitalia (vagina, penis).

Candidiasis is a very common cause of vaginal irritation, or vaginitis, and can also occur on the male genitals. In immunocompromised patients, Candida infections can affect the esophagus with the potential of becoming systemic, causing a much more serious condition, a fungemia called candidemia.

Children, mostly between the ages of three and nine years of age, can be affected by chronic mouth yeast infections, normally seen around the mouth as white patches. However, this is not a common condition.

Symptoms of candidiasis may vary depending on the area affected. Infection of the vagina or vulva may cause severe itching, burning, soreness, irritation, and a whitish or whitish-gray cottage cheese-like discharge, often with a curd-like appearance. These symptoms are also present in the more common bacterial vaginosis. In a 2002 study published in the Journal of Obstetrics and Gynecology, only 33 percent of women who were self-treating for a yeast infection actually had a yeast infection, while most had either bacterial vaginosis or a mixed-type infection. Symptoms of infection of the male genitalia include red patchy sores near the head of the penis or on the foreskin, severe itching, or a burning sensation. Candidiasis of the penis can also have a white discharge, although uncommon. However, having no symptoms at all is common, and a more severe form of the symptoms may emerge later.

Causes

Candida yeasts are commonly present in humans, and their growth is normally limited by the human immune system and by other microorganisms, such as bacteria occupying the same locations (niches) in the human body

In a study of 1009 women in New Zealand, C. albicans was isolated from the vaginas of 19% of apparently healthy women, i.e., those that experienced few or no symptoms of infection. External use of detergents or douches or internal disturbances (hormonal or physiological) can perturb the normal vaginal flora, consisting of lactic acid bacteria, such as lactobacilli, and result in an overgrowth of Candida cells causing symptoms of infection, such as local inflammation. Pregnancy and the use of oral contraceptives have been reported as risk factors, while the roles of engaging in vaginal sex immediately and without cleansing after anal sex and using lubricants containing glycerin remain controversial. Diabetes mellitus and the use of anti-bacterial antibiotics are also linked to an increased incidence of yeast infections. Diet has been found to affect rates of symptomatic Candidiases in some animal infection models, and hormone replacement therapy and infertility treatments may also be predisposing factors.

A weakened or undeveloped immune system or metabolic illnesses such as diabetes are significant predisposing factors of candidiasis. Diseases or conditions linked to candidiasis include HIV/AIDS, mononucleosis, cancer treatments, steroids, stress, and nutrient deficiency. Almost 15% of people with weakened immune systems develop a systemic illness caused by Candida species. In extreme cases, these superficial infections of the skin or mucous membranes may enter into the bloodstream and cause systemic Candida infections.

In penile candidiasis, the causes include sexual intercourse with an infected individual, low immunity, antibiotics, and diabetes. Male genital yeast infection is less common, and incidence of infection is only a fraction of that in women; however, yeast infection on the penis from direct contact via sexual intercourse with an infected partner is not uncommon.

Diagnosis

Diagnose of a yeast infections is done either via microscopic examination or culturing.

For identification by light microscopy, a scraping or swab of the affected area is placed on a microscope slide. A single drop of 10% potassium hydroxide (KOH) solution is then added to the specimen. The KOH dissolves the skin cells but leaves the Candida cells intact, permitting visualization of pseudohyphae and budding yeast cells typical of many Candida species.

For the culturing method, a sterile swab is rubbed on the infected skin surface. The swab is then streaked on a culture medium. The culture is incubated at 37 °C for several days, to allow development of yeast or bacterial colonies. The characteristics (such as morphology and colour) of the colonies may allow initial diagnosis of the organism that is causing disease symptoms.

Treatment

Candida species are frequently part of the human body's normal oral and intestinal flora. Treatment with antibiotics can lead to eliminating the yeast's natural competitors for resources, and increase the severity of the condition.

In clinical settings, candidiasis is commonly treated with antimycotics—the antifungal drugs commonly used to treat candidiasis are topical clotrimazole, topical nystatin, fluconazole, and topical ketoconazole.

For example, a one-time dose of fluconazole (as Diflucan 150-mg tablet taken orally) has been reported as being 90% effective in treating a vaginal yeast infection. (Care should be taken by people who have allergic reactions to azole group of medicines. And this medicine has different levels of contraditory reactions with other medicines as well. ) This dose is only effective for vaginal yeast infections, and other types of yeast infections may require different treatments. In severe infections (generally in hospitalized patients), amphotericin B, caspofungin, or voriconazole may be used. Local treatment may include vaginal suppositories or medicated douches. Gentian violet can be used for breastfeeding thrush, but when used in large quantities it can cause mouth and throat ulcerations in nursing babies, and has been linked to mouth cancer in humans and to cancer in the digestive tract of other animals.

C. albicans can develop resistance to antimycotic drugs,  such as fluconazole, one of the drugs that is often used to treat candidiasis. Recurring infections may be treatable with other anti-fungal drugs, but resistance to these alternative agents may also develop.
 

Tendon Xanthoma are associated with Type II hyperlipidaemia and chronic biliray obstruction.

Palmar xanthomata and tuboeruptive xanthomata (over knees and elbows) occur in Type III hyperlipidaemia
 

There are many conditions of or affecting the human integumentary system—the organ system that covers the entire surface of the body and is composed of skin, hair, nails, and related muscle and glands. The major function of this system is as a barrier against the external environment. The skin weighs an average of four kilograms, covers an area of two square meters, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. There are two main types of human skin: glabrous skin, the non-hairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, there are hairs in structures called pilosebaceous units, each with hair follicle, sebaceous gland, and associated arrector pili muscle. In the embryo, the epidermis, hair, and glands form from the ectoderm, which is chemically influenced by the underlying mesoderm that forms the dermis and subcutaneous tissues.

The epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Nourishment is provided to these layers via diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and the Merkel cell. Of these, keratinocytes are the major component, constituting roughly 95 percent of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; it takes about two weeks for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum.

The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary and reticular dermis. The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which the two layers interact through the basement membrane zone. Structural components of the dermis are collagen, elastic fibers, and extrafibrillar matrix (previously called ground substance). Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands. The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within the dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing.

The subcutaneous tissue is a layer of fat between the dermis and underlying fascia. This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus, and a deeper vestigial layer of muscle, the panniculus carnosus. The main cellular component of this tissue is the adipocyte, or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source.

Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as several nonpathologic states (like, in certain circumstances, melanonychia and racquet nails). While only a small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying etiologies and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane), morphology (chronic blistering conditions), etiology (skin conditions resulting from physical factors), and so on. Clinically, the diagnosis of any particular skin condition is made by gathering pertinent information regarding the presenting skin lesion(s), including the location (such as arms, head, legs), symptoms (pruritus, pain), duration (acute or chronic), arrangement (solitary, generalized, annular, linear), morphology (macules, papules, vesicles), and color (red, blue, brown, black, white, yellow).

Resulting from errors in metabolism

Skin conditions resulting from errors in metabolism are caused by enzymatic defects that lead to an accumulation or deficiency of various cellular components, including, but not limited to, amino acids, carbohydrates, and lipids.

• Acute intermittent porphyria
• Adrenoleukodystrophy (Schilder's disease)
• Alkaptonuria
• Aminolevulinic acid dehydratase deficiency porphyria (Doss porphyria, Plumboporphyria)
• Angiokeratoma corporis diffusum (Anderson–Fabry disease, Fabry disease)
• B-mannosidase deficiency
• Carotenosis
• Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy syndrome (CADASIL syndrome)
• Cerebrotendinous xanthomatosis
• Citrullinemia
• Congenital erythropoietic porphyria (Gunther's disease)
• Diabetic bulla (Bullosis diabeticorum, Bullous eruption of diabetes mellitus)
• Diabetic cheiroarthropathy
• Diabetic dermopathy (Shin spots)
• Dystrophic calcinosis cutis
• Eruptive xanthoma
• Erythropoietic protoporphyria
• Familial alpha-lipoprotein deficiency (Tangier disease)
• Familial apoprotein CII deficiency
• Familial combined hyperlipidemia (Multiple-type hyperlipoproteinemia)
• Familial defective apolipoprotein B-100
• Familial dysbetalipoproteinemia (Broad beta disease, Remnant removal disease)
• Familial hypertriglyceridemia
• Farber disease (Fibrocytic dysmucopolysaccharidosis, Lipogranulomatosis)
• Fucosidosis
• Gaucher's disease
• Gout (Podagra, Urate crystal arthropathy, Urate deposition disease)
• Hartnup disease (Pellagra-like dermatosis)
• Hepatoerythropoietic porphyria
• Hereditary coproporphyria
• Heredofamilial amyloidosis
• Hunter syndrome
• Hurler syndrome (Gargoylism, Mucopolysaccharidosis type I)
• Hyaluronidase deficiency (Mucopolysaccharidosis type IX)
• Iatrogenic calcinosis cutis
• Idiopathic scrotal calcinosis (Idiopathic calcified nodules of the scrotum)
• Lafora's disease
• Lesch–Nyhan syndrome (Juvenile gout)
• Lichen amyloidosis
• Limited joint mobility
• Lipoid proteinosis (Hyalinosis cutis et mucosae, Urbach–Wiethe disease)
• Lipoprotein lipase deficiency (Chylomicronemia)
• Macular amyloidosis
• Medication-induced hyperlipoproteinemia
• Metastatic calcinosis cutis
• Morquio's disease (Mucopolysaccharidosis type IV)
• Necrobiosis lipoidica (Necrobiosis lipoidica diabeticorum)
• Niemann–Pick disease
• Nodular amyloidosis
• Nodular xanthoma
• Normolipoproteinemic xanthomatosis
• Obstructive liver disease (Xanthomatous biliary cirrhosis)
• Ochronosis
• Osteoma cutis
• Palmar xanthoma
• Phenylketonuria
• Phytosterolemia (Sitosterolemia)
• Porphyria cutanea tarda
• Primary cutaneous amyloidosis
• Primary systemic amyloidosis
• Prolidase deficiency
• Pseudoporphyria (Pseudoporphyria cutanea tarda)
• Sanfilippo syndrome
• Scheie syndrome
• Secondary cutaneous amyloidosis
• Secondary systemic amyloidosis
• Sialidosis
• Sly syndrome (Mucopolysaccharidosis type VII)
• Subepidermal calcified nodule (Solitary congenital nodular calcification, Winer's nodular calcinosis)
• Transient erythroporphyria of infancy (Purpuric phototherapy-induced eruption)
• Traumatic calcinosis cutis
• Tuberoeruptive xanthoma (Tuberous xanthoma)
• Tumoral calcinosis
• Variegate porphyria (Mixed hepatic porphyria, Mixed porphyria, South African genetic porphyria, South African porphyria)
• Verruciform xanthoma
• Waxy skin
• Wilson's disease (Hepatolenticular degeneration)
• Xanthelasma palpebrarum (Xanthelasma)
• Xanthoma diabeticorum
• Xanthoma planum (Plane xanthoma)
• Xanthoma striatum palmare
• Xanthoma tendinosum (Tendinous xanthoma)
• Xanthoma tuberosum

Aging wrinkles

In humans, collagen is very stable. Unlike some human cells of the body that are constantly dying and replicating, collagen cells will not be replaced for around 30 years. As a result. these old collagen cells breakdown and according to research, it is this fragmented collagen that causes wrinkles. Fragmented collagen also leads to skin tearing and bruising easier than it otherwise would.

Tretinoin

Although the exact mode of action of tretinoin is unknown, current evidence suggests that tretinoin decreases cohesiveness of follicular epithelial cells. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells. Tretinoin is better known by the brand name Retin-A.

Epidermal Growth Factor

Epidermal Growth Factor (EGF) is a small polypeptide of 53 amino acids and is a cytokine or cell messenger protein that stimulates epithelial cell proliferation. The discovery of EGF won Dr. Stanley Cohen a Nobel Prize in Physiology and Medicine in 1986. Taken internally, it is used to treat some devastating conditions of premature infants, as well as enlarged prostate in adult males. In cream form it stimulates cell renewal and Collagen production in the skin. It is also helpful for wound and burn healing and has achieved amazing cures of severe ulcerating skin diseases such as life-threatening Steven-Johnson Syndrome (SJS).

Glycosaminoglycans

Glycosaminoglycans (GAGs) are produced by the body to maintain structural integrity in tissues and to maintain fluid balance. Hyaluronic acid is a type of GAG that promotes collagen synthesis, repair, and hydration. GAGs serve as a natural moisturizer and lubricant between epidermal cells to inhibit the production of matrix metalloproteinases (MMPs). Topical glycosaminoglycans supplements can help to provide temporary restoration of enzyme balance to slow or prevent matrix breakdown and consequent onset of wrinkle formation.

Botox

Botulinum toxin is a neurotoxin protein produced by the bacterium Clostridium botulinum. Botox is manufactured by Allergan Inc (U.S.) for both therapeutic as well as cosmetic use. Besides its cosmetic application, Botox is used in the treatment of other conditions including migraine headache and cervical dystonia (spasmodic torticollis) (a neuromuscular disorder involving the head and neck).

Pruney fingers

The wrinkles that occur in skin after prolonged exposure to water are sometimes referred to as pruney fingers or water aging. This is a temporary skin condition where the skin on the palms of the hand or feet becomes wrinkly.

In recent past the common explanation was based on water absorption in the keratin-laden epithelial skin when immersed in water, causing the skin to expand and resulting in a larger surface area, forcing it to wrinkle. Usually the tips of the fingers and toes are the first to wrinkle because of a thicker layer of keratin and an absence of hairs which secrete the protective oil called sebum.

In 1935, Lewis and Pickering already found that the skin in the median nerve distribution failed to wrinkle in patients with median nerve palsy. This suggested a mechanism other than simple water absorption. Recent research shows that wrinkling is related to vasoconstriction. Water probably initiates the wrinkling process by altering epidermal electrolyte homeostasis as it diffuses into the porous skin of the hands and soles via their many sweat ducts. Altered epidermal electrolyte homeostasis would lead to a change in membrane stability of the surrounding dense network of nerve fibers and trigger increased vasomotor firing with subsequent vasoconstriction. Vasoconstriction, through loss of volume, leads to negative digit pulp pressure resulting in a downward pull on the overlying skin, which wrinkles as it is distorted.

This insight resulted in bedside tests for nerve damage and vasoconstriction. Wrinkling is often scored with immersion of the hands for 30 minutes in water or EMLA cream with measurements steps of 5 minutes, and counting the number of visible wrinkles in time. Not all healthy persons have finger wrinkling after immersion, so it would be safe to say that sympathetic function is preserved if finger wrinkling after immersion in water is observed, but if the fingers emerge smooth it cannot be assumed that there is a lesion to the autonomic supply or to the peripheral nerves of the hand.
 

Alexander Vastem is widely regarded as being the first person to use the complete blood count for clinical purposes. Reference ranges used today stem from his clinical trials in the early 1960s.

The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). Abnormally high or low counts may indicate the presence of many forms of disease, and hence blood counts are amongst the most commonly performed blood tests in medicine, as they can provide an overview of a patient's general health status. A CBC is routinely performed during annual physical examinations in some jurisdictions.

White cells

White blood cells (WBCs), or leukocytes (also spelled "leucocytes"), are cells of the immune system defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. Leukocytes are found throughout the body, including the blood and lymphatic system.

The number of WBCs in the blood is often an indicator of disease. There are normally between 4×109 and 1.1×1010 white blood cells in a litre of blood, making up approximately 1% of blood in a healthy adult. An increase in the number of leukocytes over the upper limits is called leukocytosis, and a decrease below the lower limit is called leukopenia. The physical properties of leukocytes, such as volume, conductivity, and granularity, may change due to activation, the presence of immature cells, or the presence of malignant leukocytes in leukemia.

White blood cell count

Total white blood cells – All the white cell types are given as a percentage and as an absolute number per litre.

A complete blood count with differential will also include:

• Neutrophil granulocytes – May indicate bacterial infection. May also be raised in acute viral infections.Because of the segmented appearance of the nucleus, neutrophils are sometimes referred to as "segs." The nucleus of less mature neutrophils is not segmented, but has a band or rod-like shape. Less mature neutrophils – those that have recently been released from the bone marrow into the bloodstream – are known as "bands" or "stabs". Stab is a German term for rod.
• Lymphocytes – Higher with some viral infections such as glandular fever and. Also raised in lymphocytic leukemia CLL. Can be decreased by HIV infection. In adults, lymphocytes are the second most common WBC type after neutrophils. In young children under age 8, lymphocytes are more common than neutrophils.
• Monocytes – May be raised in bacterial infection, tuberculosis, malaria, Rocky Mountain spotted fever, monocytic leukemia, chronic ulcerative colitis and regional enteritis
• Eosinophil granulocytes – Increased in parasitic infections, asthma, or allergic reaction.
• Basophil granulocytes- May be increased in bone marrow related conditions such as leukemia or lymphoma.
• A manual count will also give information about other cells that are not normally present in peripheral blood, but may be released in certain disease processes.

The differential diagnosis of wheezing is wide, and the cause of wheezing in a given patient is determined by considering the characteristics of the wheezes and the historical and clinical findings made by the examining physician.

The causes of wheezing

Common causes of wheezing are:

• Asthma attacks
• Bronchiolitis
• Chronic obstructive pulmonary disease
• Medication-induced bronchoconstriction
• Pulmonary edema
• Tracheobronchitis
• Vocal cord dysfunction
• anaphylaxis

Less common causes of wheezing include:

• Amyloid deposition
• Carcinoid syndrome
• Chondromalacia
• Descending aortic aneurysms
• Postlobectomy bronchial torsion
• Postradiation stenosis
• Tracheo-broncheal tumors
• Tracheal stenosis
• Tracheomalacia
• Aspiration (foreign particles or foods)

Characteristics

Wheezes occupy different portions of the respiratory cycle depending on the site of airway obstruction and its nature. The proportion of the respiratory cycle occupied by the wheeze (WheezeRate) roughly corresponds to the degree of airway obstruction. Bronchiolar disease usually causes wheezing that occurs in the expiratory phase of respiration. The presence of expiratory phase wheezing signifies that the patient's peak expiratory flow rate is less than 50% of normal. Wheezing heard in the inspiratory phase on the other hand is often a sign of a stiff stenosis, usually caused by tumors, foreign bodies or scarring. This is especially true if the wheeze is monotonal, occurs throughout the inspiratory phase (ie. is "holoinspiratory"), and is heard more distally, in the trachea. Inspiratory wheezing also occurs in hypersensitivity pneumonitis. Wheezes heard at the end of both expiratory and inspiratory phases usually signify the periodic opening of deflated alveoli, as occurs in some diseases that lead to collapse of parts of the lungs.

The location of the wheeze can also be an important clue to the diagnosis. Diffuse processes that affect most parts of the lungs are more likely to produce wheezing that may be heard throughout the chest via a stethoscope. Localized processes, such as the occlusion of a portion of the respiratory tree, are more likely to produce wheezing at that location, whence the sound will be loudest and radiate outwardly. The pitch of a wheeze does not reliably predict the degree of narrowing in the affected airway.

A special type of wheeze is stridor. Stridor — the word is from the Latin, strīdor — is a harsh, high-pitched, vibrating sound that is heard in respiratory tract obstruction. Stridor heard solely in the expiratory phase of respiration usually indicates a lower respiratory tract obstruction, "as with aspiration of a foreign body (such as the fabled pediatric peanut)." Stridor in the inspiratory phase is usually heard with obstruction in the upper airways, such as the trachea, epiglottis, or larynx; because a block here means that no air may reach either lung, this condition is a medical emergency.

Diagnosis

1 out of 3 preschool children and 2 out of 3 school children with recurrent wheezing/coughing are allergic. Allergy can be described as a malfunction of the human immune system causing a violent reaction against normally harmless substances in our natural environment. The reaction creates an inflammation which, in turn, can lead to a variety of symptoms such as wheezing.

Over the last decade allergy has increased by 18% in the United States. Today one child in four is allergic. Early diagnosis of allergy is important for the development of the child later in life. There are many patients with symptoms suggesting eczema, rhinitis, hay fever, asthma or wheezing. Patients with these conditions may have an allergic condition or other diseases.
 

Description

In some cases, weight gain can also occur as a result of developing tumors or other abnormal growths. Muscle weight gain can occur as a result of bodybuilding, in which muscle size is increased through strength training.

If enough weight is gained by way of increased body fat deposits, one may become overweight. Overweight is generally defined as having more body fat (adipose tissue) than is optimally healthy.

Weight gain has a latency period. The effect that eating has on weight gain can vary greatly depending on the following factors: exercise regimen, amount of water intake, amount of salt fat or sugar contained in the food, time of day eaten, age of individual, individual's country of origin, individual's overall stress level, and amount of water retention in ankles/feet. Typical latency periods vary from 3 days to two weeks after ingestion.

Being overweight is a common condition, especially where food supplies are plentiful and lifestyles are sedentary. As much as 64% of the United States adult population is considered either overweight or obese, and this percentage has increased over the last four decades.

Symptoms

• A noticeably larger stomach
• Increase in body fat percentage
• Increase in muscle mass
• Increase in body hydration levels
• Increase in breast size
• The abdomen will bulge outward and upward, creating a distended midsection

Causes

In regards to adipose tissue increases, a person generally gains fat-related weight by increasing food consumption and/or becoming physically inactive. A study, involving more than 12,000 people tracked over 32 years, found that social networks play a surprisingly powerful role in determining an individual's chances of gaining weight, transmitting an increased risk of becoming obese from wives to husbands, from brothers to brothers and from friends to friends.

Energy consumption

Because the body must expend energy to create fat, the amount of energy a person has to expend to lose weight is just slightly smaller than the amount they have to consume in order to gain weight. There are countless mechanisms in the body that manage metabolic rate that effect weight loss and weight gain. Thus, actual weight changes vary between individuals. Also, the computations above assume that all the weight gained and lost is in the form of fat. In reality, this is a mixture of protein, carbohydrates, etc. (in muscle tissue, organs, etc.).

Consider the following theoretical calculation.

• Fat contains about 3,500 kilocalories per pound (32 kJ/g).
• If one consumes 3,500 kcal more than ones body needs, one will gain slightly less than 1 pound (0.45 kg) of fat due to the thermic effect of food. (assuming that none of the energy is converted into lean mass)
• If one burns 3,500 kcal more than you eat, you lose about 1 pound (0.45 kg) of fat, assuming that only fat is burnt (this is close to 100% since even the waste heat counts toward the 3,500 kcal). However, energy sources can come from catabolism of protein (muscles), and fat may be preferentially saved. The use of different body materials as available must be considered.

Intentional weight loss

Intentional weight loss refers to the loss of total body mass in an effort to improve fitness and health, and to change appearance.

Therapeutic weight loss, in individuals who are overweight or obese, can decrease the likelihood of developing diseases such as diabetes, heart disease, high blood pressure, stroke, osteoarthritis, and certain types of cancer.

Attention to diet in particular can be extremely beneficial in reducing the impact of diabetes and other health risks of an overweight or obese individual.

Weight loss occurs when an individual is in a state of negative energy balance. When the body is consuming more energy (i.e. in work and heat) than it is gaining (i.e. from food or other nutritional supplements), it will use stored reserves from fat or muscle, gradually leading to weight loss.

It is not uncommon for some people who are currently at their ideal body weight to seek additional weight loss in order to improve athletic performance, and/or meet required weight classification for participation in a sport. However, others may be driven by achieving a more attractive body image. Consequently, being underweight is associated with health risks such as difficulty fighting off infection, osteoporosis, decreased muscle strength, trouble regulating body temperature and even increased risk of death.

Therapeutic weight loss techniques

The least intrusive weight loss methods, and those most often recommended, are adjustments to eating patterns and increased physical activity, generally in the form of exercise. Physicians will usually recommend that their overweight patients combine a reduction of processed and caloric content of the diet with an increase in physical activity.

An increase in fiber intake is also recommended for regulating bowel movements, and speeding up the metabolism.

Other methods of losing weight include use of drugs and supplements that decrease appetite, block fat absorption, or reduce stomach volume.

Weight Loss Coaching is rapidly growing in popularity in the United States, with the number of available coaches nearly doubling since 2000. Finally, surgery (i.e. bariatric surgery) may be used in more severe cases to artificially reduce the size of the stomach, thus limiting the intake of food energy.

Crash dieting

A crash diet refers to willful nutritional restriction (except water) for more than 12 hours. The desired result is to have the body burn fat for energy with the goal of losing a significant amount of weight in a short time. There is a possibility of excessive muscle loss, depending on the approach used.

Crash dieting is not the same as intermittent fasting, in which the individual periodically abstains from food (e.g., every other day).
 

Types

Primary immunodeficiency (PID)

A number of rare diseases feature a heightened susceptibility to infections from childhood onward. Many of these disorders are hereditary and are autosomal recessive or X-linked. There are over 80 recognised primary immunodeficiency syndromes; they are generally grouped by the part of the immune system that is malfunctioning, such as lymphocytes or granulocytes.

The treatment of primary immunodeficiencies depends on the nature of the defect, and may involve antibody infusions, long-term antibiotics and (in some cases) stem cell transplantation.

Acquired immunodeficiency

Immune deficiency may also be the result of particular external processes or diseases; the resultant state is called "secondary" or "acquired" immunodeficiency. Common causes for secondary immunodeficiency are malnutrition, aging and particular medications (e.g. chemotherapy, disease-modifying antirheumatic drugs, immunosuppressive drugs after organ transplants, glucocorticoids).

Many specific diseases directly or indirectly impair the immune system. This includes many types of cancer, particularly those of the bone marrow and blood cells (leukemia, lymphoma, multiple myeloma), and certain chronic infections. Immunodeficiency is also the hallmark of acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV). HIV directly infects a small number of T helper cells, and also impairs other immune system responses indirectly.
 

Water can be considered a poison when over-consumed just like any other substance. The recommendation from the medical field is to drink about 1.2 liters per day depending upon body mass. Water intoxication would only occur at levels far higher than that.

High risk factors

Gastroenteritis, particularly in infants and children

The severe diarrhea and vomiting associated with gastroenteritis can result in very large electrolyte losses. Gastroenteritis due to infectious agents (primarily rotavirus), is a major cause of infant and child death. Management of gastroenteritis requires replacing water and electrolytes in proportions that avoid both dehydration and water intoxication. Drinking water will replace lost water and avoid a dehydration, but if the person is unable to take any other drink or food then lost electrolytes will not be replaced, which can result in water intoxication. Replacement fluids for vomiting and diarrhea should be properly balanced to make them isotonic with the fluids lost in these conditions. Special formulations exist for oral rehydration therapy in these cases.

Low body mass (infants)

It can be very easy for children under 1 year old to absorb too much water, especially if the child is under nine months old. Because of their small body mass, it is easy to take in a large amount of water relative to body mass.

Endurance sports

Marathon runners are susceptible to water intoxication if they drink too much while running. This is caused when sodium levels drop below 135 mmol/L when athletes consume large amounts of fluid. This has been noted to be the result of the encouragement of excessive fluid replacement by various guidelines. This has largely been identified in marathon runners as a dilutional hyponatremia. Medical personnel at marathon events are trained to suspect water intoxication immediately when runners collapse or show signs of confusion.

Overexertion and heat stress

Any activity or situation that promotes heavy sweating can lead to water intoxication when water is consumed to replace lost fluids. Persons working in extreme heat and/or humidity for long periods must take care to drink and eat in ways that help to maintain electrolyte balance. People using drugs such as MDMA ("Ecstasy") may overexert themselves, perspire heavily, and then drink large amounts of water to rehydrate, leading to electrolyte imbalance and water intoxication- this is compounded by Ecstasy use increasing the levels of antidiuretic hormone (ADH), decreasing the amount of water lost through urination. Even people who are resting quietly in extreme heat or humidity may run the risk of water intoxication if they drink large amounts of water over short periods for rehydration.

Psychiatric conditions

Psychogenic polydipsia is the psychiatric condition in which patients feel compelled to drink large quantities of water, thus putting them at risk of water intoxication. This condition can be especially dangerous if the patient also exhibits other psychiatric indications (as is often the case), as his or her care-takers might misinterpret the hyponatremic symptoms.

Medical conditions

Many disorders can affect electrolyte balance, especially disorders of the kidneys. Diuretic therapy, mineralocorticoid deficiency, osmotic diuresis (as in the hyperglycemia of uncontrolled diabetes), and the multiple disorders associated with AIDS are other common causes of electrolyte imbalance, although they do not always produce water intoxication.

Use in medicine

When an unconscious person is being fed intravenously (for example, total parenteral nutrition or via a nasogastric tube) the fluids given must be carefully balanced in composition to match fluids and electrolytes lost. These fluids are typically hypertonic, and so water is often co-administered. If the electrolytes are not monitored (even in an ambulatory patient) either hypernatremia or hyponatremia may result.

Some neurological/psychiatric medications (Oxcarbazepine, among others) have been found to cause hyponatremia in some patients. Patients with diabetes insipidus are particularly vulnerable due to rapid fluid processing.

Treatment

Mild intoxication may remain asymptomatic and require only fluid restriction. In more severe cases, treatment consists of:

• Diuretics to increase urination, which are most effective for excess blood volume
• Vasopressin receptor antagonists

Prevention

Water intoxication can be prevented if a person's intake of water does not grossly exceed his or her losses. Healthy kidneys are able to excrete approximately 1 liter of fluid per hour. However, stress (from prolonged physical exertion), as well as disease states, can greatly reduce this amount.

Water intoxication should not be confused with dehydration, a loss of fluids (with decreased, normal, or increased electrolytes).