Electrolytes Health Dictionary

Diarrhoea or looseness of the bowels is increased frequency, ?uidity or volume of bowel movements compared to usual. Most people have occasional attacks of acute diarrhoea, usually caused by contaminated food or water or excessive alcohol consumption. Such attacks normally clear up within a day or two, whether or not they are treated. Chronic diarrhoea, on the other hand, may be the result of a serious intestinal disorder or of more general disease.

The commonest cause of acute diarrhoea is food poisoning, the organisms involved usually being STAPHYLOCOCCUS, CLOSTRIDIUM bacteria, salmonella, E. coli O157 (see ESCHERICHIA), CAMPYLOBACTER, cryptosporidium, and Norwalk virus. A person may also acquire infective diarrhoea as a result of droplet infections from adenoviruses or echoviruses. Interference with the bacterial ?ora of the intestine may cause acute diarrhoea: this often happens to someone who travels to another country and acquires unfamiliar intestinal bacteria. Other infections include bacillary dysentery, typhoid fever and paratyphoid fevers (see ENTERIC FEVER). Drug toxicity, food allergy, food intolerance and anxiety may also cause acute diarrhoea, and habitual constipation may result in attacks of diarrhoea.

Treatment of diarrhoea in adults depends on the cause. The water and salts (see ELECTROLYTES) lost during a severe attack must be replaced to prevent dehydration. Ready-prepared mixtures of salts can be bought from a pharmacist. Antidiarrhoeal drugs such as codeine phosphate or loperamide should be used in infectious diarrhoea only if the symptoms are disabling. Antibacterial drugs may be used under medical direction. Persistent diarrhoea – longer than a week – or blood-stained diarrhoea must be investigated under medical supervision.

Diarrhoea in infants can be such a serious condition that it requires separate consideration. One of its features is that it is usually accompanied by vomiting; the result can be rapid dehydration as infants have relatively high ?uid requirements. Mostly it is causd by acute gastroenteritis caused by various viruses, most commonly ROTAVIRUSES, but also by many bacteria. In the developed world most children recover rapidly, but diarrhoea is the single greatest cause of infant mortality worldwide. The younger the infant, the higher the mortality rate.

Diarrhoea is much more rare in breast-fed babies, and when it does occur it is usually less severe. The environment of the infant is also important: the condition is highly infectious and, if a case occurs in a maternity home or a children’s hospital, it tends to spread quickly. This is why doctors prefer to treat such children at home but if hospital admission is essential, isolation and infection-control procedures are necessary.

Treatment An infant with diarrhoea should not be fed milk (unless breast-fed, when this should continue) but should be given an electrolyte mixture, available from pharmacists or on prescription, to replace lost water and salts. If the diarrhoea improves within 24 hours, milk can gradually be reintroduced. If diarrhoea continues beyond 36–48 hours, a doctor should be consulted. Any signs of dehydration require urgent medical attention; such signs include drowsiness, lack of response, loose skin, persistent crying, glazed eyes and a dry mouth and tongue.... diarrhoea

The outer covering of the two adrenal glands that lie atop each kidney. Embryonically derived from gonad tissue, they make steroid hormones that control electrolytes, the management of fuels, the rate of anabolism, the general response to stress, and maintenance of nonspecific resistance.... adrenal cortex

Initial treatment of acute DIARRHOEA is to prevent or correct the loss of ?uid and ELECTROLYTES from the body. This is a priority especially in infants and elderly people. Rehydration can be achieved orally or, in severe cases, by urgent admission to hospital for the replacement of ?uid and electrolytes.

For adults with acute diarrhoea, short-term symptomatic treatment can be achieved with antimotility drugs such as codeine phosphate, co-phenotrope or loperamide hydrochloride. Adsorbent drugs, for example, KAOLIN, should not be used in acute diarrhoea, but bulk-forming drugs – ispaghula or methylcellulose

– can help to control the consistency of faeces in patients with ileostomies and colostomies (see ILEOSTOMY; COLOSTOMY), or those with diarrhoea caused by DIVERTICULAR DISEASE.

Irritable bowel syndrome, malabsorption syndrom, ulcerative colitis, Crohn’s disease and diverticular disease are often accompanied by diarrhoea; for more information on these conditions, see under separate entries.

ANTIBIOTICS may sometimes cause diarrhoea and this side-e?ect should be borne in mind when the cause of the condition is being investigated.... antidiarrhoeal treatments

ASPIRIN is a commonly available analgesic (see ANALGESICS) which is frequently taken in overdose. Clinical features of poisoning include nausea, vomiting, TINNITUS, ?ushing, sweating, HYPERVENTILATION, DEHYDRATION, deafness and acid-base and electrolyte disturbances (see ELECTROLYTES). In more severe cases individuals may be confused, drowsy and comatose. Rarely, renal failure (see KIDNEYS, DISEASES OF), PULMONARY OEDEMA or cardiovascular collapse occur. Severe toxicity may be delayed, as absorption of the drug may be prolonged due to the formation of drug concretions in the stomach. Treatment involves the repeated administration of activated CHARCOAL, monitoring of concentration of aspirin in the blood, and correction of acid-base and electrolyte imbalances. In more severely poisoned patients, enhanced excretion of the drug may be necessary by alkalinising the urine (by intravenous administration of sodium bicarbonate – see under SODIUM) or HAEMODIALYSIS.... aspirin poisoning

Blood consists of cellular components suspended in plasma. It circulates through the blood vessels, carrying oxygen and nutrients to the organs and removing carbon dioxide and other waste products for excretion. In addition, it is the vehicle by which hormones and other humoral transmitters reach their sites of action.

Composition The cellular components are red cells or corpuscles (ERYTHROCYTES), white cells (LEUCOCYTES and lymphocytes – see LYMPHOCYTE), and platelets.

The red cells are biconcave discs with a diameter of 7.5µm. They contain haemoglobin

– an iron-containing porphyrin compound, which takes up oxygen in the lungs and releases it to the tissue.

The white cells are of various types, named according to their appearance. They can leave the circulation to wander through the tissues. They are involved in combating infection, wound healing, and rejection of foreign bodies. Pus consists of the bodies of dead white cells.

Platelets are the smallest cellular components and play an important role in blood clotting (see COAGULATION).

Erythrocytes are produced by the bone marrow in adults and have a life span of about 120 days. White cells are produced by the bone

marrow and lymphoid tissue. Plasma consists of water, ELECTROLYTES and plasma proteins; it comprises 48–58 per cent of blood volume. Plasma proteins are produced mainly by the liver and by certain types of white cells. Blood volume and electrolyte composition are closely regulated by complex mechanisms involving the KIDNEYS, ADRENAL GLANDS and HYPOTHALAMUS.... blood

The several blood factors that enable the acid waste products of metabolism to be carried in the alkaline blood without disrupting its chemistry. These include carbolic acid, carbonates, phosphates, electrolytes, blood proteins, and erythrocyte membranes.... buffering system

A fall in the water content of the body. Sixty per cent of a man’s body weight is water, and 50 per cent of a woman’s; those proportions need to be maintained within quite narrow limits to ensure proper functioning of body tissues. Body ?uids contain a variety of mineral salts (see ELECTROLYTES) and these, too, must remain within narrow concentration bands. Dehydration is often accompanied by loss of salt, one of the most important minerals in the body.

The start of ‘dehydration’ is signalled by a person becoming thirsty. In normal circumstances, the drinking of water will relieve thirst and serious dehydration does not develop. In a temperate climate an adult will lose 1.5 litres or more a day from sweating, urine excretion and loss of ?uid through the lungs. In a hot climate the loss is much higher – up to 10 litres if a person is doing hard physical work. Even in a temperate climate, severe dehydration will occur if a person does not drink for two or three days. Large losses of ?uid occur with certain illnesses – for example, profuse diarrhoea; POLYURIA in diabetes or kidney failure (see KIDNEYS, DISEASES OF); and serious blood loss from, say, injury or a badly bleeding ULCER in the gastrointestinal tract. Severe thirst, dry lips and tongue, TACHYCARDIA, fast breathing, lightheadedness and confusion are indicative of serious dehydration; the individual can lapse into COMA and eventually die if untreated. Dehydration also results in a reduction in output of urine, which becomes dark and concentrated.

Prevention is important, especially in hot climates, where it is essential to drink water even if one is not thirsty. Replacement of salts is also vital, and a diet containing half a teaspoon of table salt to every litre of water drunk is advisable. If someone, particularly a child, suffers from persistent vomiting and diarrhoea, rehydration therapy is required and a salt-andglucose rehydration mixture (obtainable from pharmacists) should be taken. For those with severe dehydration, oral ?uids will be insu?cient and the affected person needs intravenous ?uids and, sometimes, admission to hospital, where ?uid intake and output can be monitored and rehydration measures safely controlled.... dehydration

Each kidney comprises over a million of these microscopic units which regulate and control the formation of URINE. A tuft of capillaries invaginates the Bowmans capsule, which is the blind-ending tube (GLOMERULUS) of each nephron. Plasma is ?ltered out of blood and through the Bowmans capsule into the renal tubule. As the ?ltrate passes along the tubule, most of the water and electrolytes are reabsorbed. The composition is regulated with the retention or addition of certain molecules (e.g. urea, drugs, etc.). The tubules eventually empty the ?ltrate, which by now is urine, into the renal pelvis from where it ?ows down the ureters into the bladder. (See KIDNEYS.)... nephron

Fasting is the abstention from, or deprivation of, food and drink. It may result from a genuine desire to lose weight – in an attempt to improve one’s health and/or appearance – or from a MENTAL ILLNESS such as DEPRESSION, or from one of the EATING DISORDERS. Certain religious customs and practices may demand periods of fasting. Forced fasting, often extended, has been used for many years as an e?ective means of torture.

Without food and drink the body rapidly becomes thinner and lighter as it draws upon its stored energy reserves, initially mainly fat. Body temperature gradually falls, and muscle is progressively broken down as the body struggles to maintain its vital functions. Dehydration, leading to cardiovascular collapse, inevitably follows unless a basic amount of water is taken – particularly if the body’s ?uid output is high, such as may occur with excessive sweating.

After prolonged fasting the return to food should be gradual, with careful monitoring of blood-pressure levels and concentrations of serum ELECTROLYTES. Feeding should consist mainly of liquids and light foods at ?rst, with no heavy meals being taken for several days.... fasting

In severely ill patients – especially those who have had major surgery or those with SEPSIS, burns, acute pancreatitis (see PANCREAS, DISORDERS OF) and renal failure – the body’s reserves of protein become exhausted. This results in weight loss; reduction in muscle mass; a fall in the serum albumin (see ALBUMINS) and LYMPHOCYTE count; and an impairment of cellular IMMUNITY. Severely ill patients are unable to take adequate food by mouth to repair the body protein loss so that enteral or parenteral nutrition is required. Enteral feeding is through the gastrointestinal tract with the aid of a nasogastric tube; parenteral nutrition involves the provision of carbohydrate, fat and proteins by intravenous administration.

The preferred route for the infusion of hyperosmolar solutions is via a central venous catheter (see CATHETERS). If parenteral nutrition is required for more than two weeks, it is advisable to use a long-term type of catheter such as the Broviac, Hickman or extra-corporeal type, which is made of silastic material and is inserted via a long subcutaneous tunnel; this not only helps to ?x the catheter but also minimises the risk of ascending infection.

Dextrose is considered the best source of carbohydrate and may be used as a 20 per cent or 50 per cent solution. AMINO ACIDS should be in the laevo form and should contain the correct proportion of essential (indispensable) and non-essential amino acids. Preparations are available with or without electrolytes and with or without fat emulsions.

The main hazards of intravenous feeding are blood-borne infections made possible by continued direct access to the circulation, and biochemical abnormalities related to the composition of the solutions infused. The continuous use of hypertonic solutions of glucose can cause HYPERGLYCAEMIA and glycosuria and the resultant POLYURIA may lead to dehydration. Treatment with INSULIN is needed when hyper-osmolality occurs, and in addition the water and sodium de?cits will require to be corrected.... parenteral nutrition

n. the main part of the large intestine, which consists of four sections – the ascending, transverse, descending, and sigmoid colons (see illustration). The colon has no digestive function but it absorbs large amounts of water and electrolytes from the undigested food passed on from the small intestine. At intervals strong peristaltic movements move the dehydrated contents (faeces) towards the rectum. —colonic adj.... colon

A state of acute circulatory failure in which the heart’s output of blood is inadequate to provide normal PERFUSION of the major organs. It is accompanied by a fall in arterial blood pressure and is characterised by systemic arterial hypotension (arterial blood pressure less than 80 mm of mercury), sweating and signs of VASOCONSTRICTION (for example, pallor, CYANOSIS, a cold clammy skin and a low-volume pulse). These signs may be associated with clinical evidence of poor tissue perfusion, for example to the brain and kidneys, leading to mental apathy, confusion or restlessness and OLIGURIA.

Shock may result from loss of blood or plasma volume. This may occur as a result of haemorrhage or severe diarrhoea and vomiting. It may also result from peripheral pooling of blood due to such causes as TOXAEMIA or ANAPHYLAXIS. The toxaemia is commonly the result of a SEPTICAEMIA in which leakage through capillaries reduces circulating blood volume. Another form is called cardogenic shock, and is due to failure of the heart as a pump. It is most commonly seen as a result of myocardial infarction (see under HEART, DISEASES OF).

If failure of adequate blood ?ow to vital organs is prolonged, the effects can be disastrous. The ischaemic intestine permits the transfer of toxic bacterial products and proteins across its wall into the blood; renal ISCHAEMIA prevents the maintenance of a normal electrolyte and acid-base balance.

Treatment If the shock is a result of haemorrhage or diarrhoea or vomiting, replacement of blood, lost ?uid and electrolytes is of prime importance. If it is due to septicaemia, treatment of the infection is of paramount importance, and in addition, intravenous ?uids and vasopressor drugs will be required. Cardiogenic shock is treated by attention to the underlying cause. Full intensive care is likely to be required, and arti?cial ventilation and DIALYSIS may both be needed.... shock

The membrane which envelops the outer surface of the body, meeting at the body’s various ori?ces, with the mucous membrane lining the internal cavities.

Structure

CORIUM The foundation layer. It overlies the subcutaneous fat and varies in thickness from 0·5–3.0 mm. Many nerves run through the corium: these have key roles in the sensations of touch, pain and temperature (see NEURON(E)). Blood vessels nourish the skin and are primarily responsible for regulating the body temperature. Hairs are bedded in the corium, piercing the epidermis (see below) to cover the skin in varying amounts in di?erent parts of the body. The sweat glands are also in the corium and their ducts lead to the surface. The ?brous tissue of the corium comprises interlocking white ?brous elastic bundles. The corium contains many folds, especially over joints and on the palms of hands and soles of feet with the epidermis following the contours. These are permanent throughout life and provide unique ?ngerprinting identi?cation. HAIR Each one has a root and shaft, and its varying tone originates from pigment scattered throughout it. Bundles of smooth muscle (arrectores pilorum) are attached to the root and on contraction cause the hair to stand vertical. GLANDS These occur in great numbers in the skin. SEBACEOUS GLANDS secrete a fatty substance and sweat glands a clear watery ?uid (see PERSPIRATION). The former are made up of a bunch of small sacs producing fatty material that reaches the surface via the hair follicle. Around three million sweat or sudoriparous glands occur all over the body surface; sited below the sebaceous glands they are unconnected to the hairs. EPIDERMIS This forms the outer layer of skin and is the cellular layer covering the body surface: it has no blood vessels and its thickness varies from 1 mm on the palms and soles to 0·1 mm on the face. Its outer, impervious, horny layer comprises several thicknesses of ?at cells (pierced only by hairs and sweat-gland openings) that are constantly rubbed o? as small white scales; they are replaced by growing cells from below. The next, clear layer forms a type of membrane below which the granular stratum cells are changing from their origins as keratinocytes in the germinative zone, where ?ne sensory nerves also terminate. The basal layer of the germinative zone contains melanocytes which produce the pigment MELANIN, the cause of skin tanning.

Nail A modi?cation of skin, being analagous to the horny layer, but its cells are harder and more adherent. Under the horny nail is the nail bed, comprising the well-vascularised corium (see above) and the germinative zone. Growth occurs at the nail root at a rate of around 0·5 mm a week – a rate that increases in later years of life.

Skin functions By its ability to control sweating and open or close dermal blood vessels, the skin plays a crucial role in maintaining a constant body temperature. Its toughness protects the body from mechanical injury. The epidermis is a two-way barrier: it prevents the entry of noxious chemicals and microbes, and prevents the loss of body contents, especially water, electrolytes and proteins. It restricts electrical conductivity and to a limited extent protects against ultraviolet radiation.

The Langerhans’ cells in the epidermis are the outposts of the immune system (see IMMUNITY), just as the sensory nerves in the skin are the outposts of the nervous system. Skin has a social function in its ability to signal emotions such as fear or anger. Lastly it has a role in the synthesis of vitamin D.... skin

n. fluid used in the dialysis process. In *haemodialysis the dialysate is purified tap water to which has been added a precise amount of electrolyte solution. In *peritoneal dialysis the dialysate is a commercially produced fluid containing electrolytes with glucose, glucose polymers, or amino acids.... dialysate

n. 1. the slow injection of a substance, usually into a vein (intravenous (IV) infusion). This is a common method for replacing water, electrolytes, and blood products and is also used for the continuous administration of drugs (e.g. antibiotics, painkillers) or *nutrition. See also drip. 2. the process whereby the active principles are extracted from plant material by steeping it in water that has been heated to boiling point (as in the making of tea). 3. the solution produced by this process.... infusion

a network of vessels that conveys electrolytes, water, proteins, etc. – in the form of *lymph – from the tissue fluids to the bloodstream (see illustration). It consists of fine blind-ended lymphatic capillaries, which unite to form lymphatic vessels. At various points along the lymphatic vessels are *lymph nodes. Lymph drains into the capillaries and passes into the lymphatic vessels, which have valves to prevent backflow of lymph. The lymphatics lead to two large channels – the thoracic duct and the right lymphatic duct – which return the lymph to the bloodstream via the innominate veins.... lymphatic system

The clinical state which results from renal failure (see KIDNEYS, DISEASES OF). It may be due to disease of the KIDNEYS or it may be the result of pre-renal causes where a lack of circulating blood volume inadequately perfuses the kidneys. It may result from acute necrosis in the tubules of the kidney or it may result from obstruction to the out?ow of URINE.

The word uraemia means excess UREA in the blood; however, the symptoms of renal failure are not due to the abnormal amounts of urea circulating, but rather to the electrolyte disturbances (see ELECTROLYTES) and ACIDOSIS which are associated with impaired renal function. The acidosis results from a decreased ability to ?lter hydrogen ions from blood into the glomerular ?uid: the reduced production of ammonia and phosphate means fewer ions capable of combining with the hydrogen ions, so that the total acid elimination is diminished. The fall in glomerular ?ltration also leads to retention of SODIUM and water with resulting OEDEMA, and to retention of POTASSIUM resulting in HYPERKALAEMIA.

The most important causes of uraemia are the primary renal diseases of chronic glomerular nephritis (in?ammation) and chronic PYELONEPHRITIS. It may also result from MALIGNANT HYPERTENSION damaging the kidneys and amyloid disease destroying them. Analgesic abuse can cause tubular necrosis. DIABETES MELLITUS may cause a nephropathy and lead to uraemia, as may MYELOMATOSIS and SYSTEMIC LUPUS ERYTHEMATOSUS (SLE). Polycystic kidneys and renal tuberculosis account for a small proportion of cases.

Symptoms Uraemia is sometimes classed as acute – that is, those cases in which the symptoms develop in a few hours or days – and chronic, including cases in which the symptoms are less marked and last over weeks, months, or years. There is, however, no dividing line between the two, for in the chronic variety, which may be said to consist of the symptoms of chronic glomerulonephritis, an acute attack is liable to come on at any time.

Headache in the front or back of the head, accompanied often by insomnia and daytime drowsiness, is one of the most common symptoms. UNCONSCIOUSNESS of a profound type, which may be accompanied by CONVULSIONS resembling those of EPILEPSY, is the most outstanding feature of an acute attack and is a very dangerous condition.

Still another symptom, which often precedes an acute attack, is severe vomiting without apparent cause. The appetite is always poor, and the onset of diarrhoea is a serious sign.

Treatment The treatment of the chronic type of uraemia includes all the measures which should be taken by a person suffering from chronic glomerulonephritis (see under KIDNEYS, DISEASES OF). An increasing number of these patients, especially the younger ones, are treated with DIALYSIS and/or renal TRANSPLANTATION.... uraemia

A disorder resulting from excessive retention of water in the brain. Main symptoms are dizziness, headaches, confusion and nausea. In severe cases the patient may have ?ts (see SEIZURE) or lose consciousness. Several conditions can disturb the body’s water balance causing accumulation of water in the tissues. Heart or kidney failure, CIRRHOSIS of the liver and disorders of the ADRENAL GLANDS can all result in water retention. Other causes are stress as a result of surgery, when increased secretion of antidiuretic hormone (VASOPRESSIN) by the adrenal gland may occur. Treatment is of the underlying condition and the judicious use of DIURETICS, with careful monitoring of the body’s ELECTROLYTES.... water intoxication

“Medicines that alter the process of nutrition, restoring in some unknown way the normal functions of an organ or system . . . re-establishing healthy nutritive processes” (Blakiston Medical Dictionary)

They are blood cleansers that favourably change the character of the blood and lymph to de-toxify and promote renewal of body tissue. The term has been superseded by the word ‘adaptogen’. See: ADAPTOGEN. However, since the majority of professional phytotherapists still use the term ‘alterative’, the term ‘alterative’ is used through this book to describe the particular action of the group which includes:–

Alfalfa, Bladderwrack, Blue Flag root, Burdock, Chaparral, Chicory, Clivers, Dandelion, Devil’s Claw, Echinacea, Garlic, Ginseng, Goldenseal, Gotu Kola, Marigold, Mountain Grape, Nettles, Poke root, Queen’s Delight, Red Clover, Sarsaparilla, Thuja, Turkey Corn, Wild Indigo, Yellow Dock.

English traditional formula: equal parts, Burdock, Red Clover, Yellow Dock. Place quarter of the mixture in 2 pints water; simmer gently down to 1 pint. Dose: one-third-half cup thrice daily, before meals. Effects are to enhance elimination through skin, kidneys and bowels; to provide hormone precursors, electrolytes and minerals. The above combination may also be taken in liquid extracts, tinctures or powders. ... alteratives

(vasoactive intestinal peptide) a peptide hormone and neurotransmitter found widely throughout the central nervous system and the gastrointestinal tract. It has numerous actions, including vasodilatation of blood vessels in the gut, reduction of acid secretion by the stomach, and enhanced secretion of electrolytes into the small bowel.... vip

n. a solution that produces ions (an ion is an atom or group of atoms that conduct electricity); for example, sodium chloride solution consists of free sodium and free chloride ions. In medical usage electrolyte usually means the ion itself; thus the term serum electrolyte level means the concentration of separate ions (sodium, potassium, chloride, bicarbonate, etc.) in the circulating blood. Concentrations of various electrolyte levels can be altered by many diseases, in which electrolytes are lost from the body (as in vomiting or diarrhoea) or are not excreted and accumulate (as in renal failure). When electrolyte concentrations are severely diminished they can be corrected by administering the appropriate substance by mouth or by intravenous drip. When excess of an electrolyte exists it may be removed by *dialysis or by special resins in the intestine, taken by mouth or by enema. See also anion.... electrolyte

(JGA) a microscopic structure within the kidney that is important in regulating blood pressure, body fluid, and electrolytes. It is situated in each nephron, between the afferent arteriole of the glomerulus and the returning distal convoluted tubule of the same nephron. The JGA consists of specialized cells within the distal tubule (the macula densa), which detect the amount of sodium chloride passing through the tubule and can secrete locally acting vasoconstrictor substances that act on the associated afferent arteriole to induce a reduction in filtration pressure (tubuloglomerular feedback). Modified cells within the afferent arterioles secrete *renin in response to a fall in perfusion pressure or feedback from the macula densa and form a central role in the renin-*angiotensin-aldosterone axis. Mesangial cells support and connect the macula densa and the specialized cells in the afferent arteriole and have sympathetic innervation, facilitating the renin response to sympathetic nervous stimulation.... juxtaglomerular apparatus

n. reduced or defective absorption of various nutrients in the small bowel. It commonly affects the absorption of fatty acids (causing *steatorrhoea, *bloating, and *flatulence), fat-soluble vitamins (A, D, E, and K), water-soluble vitamins (B12 and folate), *electrolytes (such as calcium and potassium), iron, and amino acids. Symptoms include weight loss, diarrhoea, failure to thrive, weakness and lethargy (due to *anaemia), *paraesthesia, swelling (oedema), and a propensity to bleeding. The commonest causes are *coeliac disease, *Crohn’s disease, *pancreatitis, *cystic fibrosis, *blind loop syndrome, chronic infection (e.g. giardiasis), and previous surgery.... malabsorption