Hypoalbuminemia (or hypoalbuminaemia) is a medical sign in which the level of albumin in the blood is abnormally low. It is a type of hypoproteinemia.

Albumin is a major protein in the human body, making up about 55-60% of total human plasma protein by mass. Many hormones, drugs, and other molecules are mostly bound to albumin in the bloodstream and must be released before becoming biologically active. For example, calcium binds to albumin and hypoalbuminemia leads to an increase in free ionized calcium.

Albumin is synthesized in the liver, and low serum albumin may be indicative of liver failure or diseases such as cirrhosis or chronic hepatitis. Hypoalbuminemia can also present as part of the nephrotic syndrome, in which protein is lost in the urine due to kidney damage. Low albumin levels can be an indicator of chronic malnutrition or protein losing enteropathy.

Hypoalbuminemia may cause generalized edema (swelling) via a decrease in oncotic pressure.

The serum albumin level is part of a standard panel of liver function tests. Levels below 3.5 grams per deciliter are generally considered low.

A low serum anion gap is frequently caused by hypoalbuminemia.

The treatment of nephrotic syndrome can be symptomatic or can directly address the injuries caused to the kidney.

Nephrotic syndrome can be associated with a series of complications that can affect an individual’s health and quality of life:

- Thromboembolic disorders: particularly those caused by a decrease in blood antithrombin III levels due to leakage. Antithrombin III counteracts the action of thrombin. Thrombosis usually occurs in the renal veins although it can also occur in arteries. Treatment is with oral anticoagulants (not heparin as heparin acts via anti-thrombin 3 which is lost in the proteinuria so it will be ineffective.) Hypercoagulopathy due to extravasation of fluid from the blood vessels (edema) is also a risk for venous thrombosis.

- Infections: The increased susceptibility of patients to infections can be a result of the leakage of immunoglobulins from the blood, the loss of proteins in general and the presence of oedematous fluid (which acts as a breeding ground for infections). The most common infection is peritonitis, followed by lung, skin and urinary infections, meningoencephalitis and in the most serious cases septicaemia. The most notable of the causative organisms are "Streptococcus pneumoniae" and "Haemophilus influenzae".

- Acute kidney failure due to hypovolemia: the loss of vascular fluid into the tissues (edema) produces a decreased blood supply to the kidneys that causes a loss of kidney function. Thus it is a tricky task to get rid of excess fluid in the body while maintaining circulatory euvolemia.

- Pulmonary edema: the loss of proteins from blood plasma and the consequent fall in oncotic pressure causes an abnormal accumulation of liquid in the lungs causing hypoxia and dyspnoea.

- Hypothyroidism: deficiency of the thyroglobulin transport protein thyroxin (a glycoprotein that is rich in iodine and is found in the thyroid gland) due to decreased thyroid binding globulin.

- Hypocalcaemia: lack of 25-hydroxycholecalciferol (the way that vitamin D is stored in the body). As vitamin D regulates the amount of calcium present in the blood a decrease in its concentration will lead to a decrease in blood calcium levels. It may be significant enough to cause tetany. Hypocalcaemia may be relative; calcium levels should be adjusted based on the albumin level and ionized calcium levels should be checked.

- Microcytic hypochromic anaemia: iron deficiency caused by the loss of ferritin (compound used to store iron in the body). It is iron-therapy resistant.

- Protein malnutrition: this occurs when the amount of protein that is lost in the urine is greater than that ingested, this leads to a negative nitrogen balance.

- Growth retardation: can occur in cases of relapse or resistance to therapy. Causes of growth retardation are protein deficiency from the loss of protein in urine, anorexia (reduced protein intake), and steroid therapy (catabolism).

- Vitamin D deficiency can occur. Vitamin D binding protein is lost.

- Cushing's Syndrome

It is known that diabetes causes changes to factors associated with coagulation and clotting, however not much is known of the risk of thromboembolism, or clots, in diabetic patients. There are some studies that show that diabetes increases the risk of thromboembolism; other studies show that diabetes does not increase the risk of thromboembolism. A study conducted in the Umea University Hospital, in Sweden, observed patients that were hospitalized due to an thromboembolism from 1997 to 1999. The researchers had access to patient information including age, sex, vein thromboembolism diagnosis, diagnostic methods, diabetes type and medical history. This study concluded that there is, in fact, an increased risk of thromboembolism development in diabetic patients, possibly due to factors associated with diabetes or diabetes itself. Diabetic patients are twice as likely to develop a thromboembolism than are non-diabetic patient. The exact mechanism of how diabetes increases the risk of clot formation remains unclear and could possibly be a future direction for study.

From previous studies, it is known that long distance air travel is associated with high risk of venous thrombosis. Long periods of inactivity in a limited amount of space may be a reason for the increased risk of blood clot formation. In addition, bent knees compresses the vein behind the knee (the popliteal vein) and the low humidity, low oxygen, high cabin pressure and consumption of alcohol concentrate the blood. A recent study, published in the British Journal of Haematology in 2014, determined which groups of people, are most at risk for developing a clot during or after a long flight. The study focused on 8755 frequent flying employees from international companies and organizations. It found that travelers who have recently undergone a surgical procedure or who have a malignant disease such as cancer or who are pregnant are most at risk. Preventative measures before flying may be taken in these at-risk groups as a solution.

Patients who have undergone kidney transplant have a high risk of developing RVT (about 0.4% to 6%). RVT is known to account for a large proportion of transplanted kidney failures due to technical problems (damage to the renal vein), clotting disorders, diabetes, consumption of ciclosporin or an unknown problem. Patients who have undergone a kidney transplant are commonly prescribed ciclosporin, an immunosuppressant drug which is known to reduce renal blood flow, increase platelet aggregation in the blood and cause damage to the endothelial tissue of the veins. In a clinical study conducted by the Nuffield Department of Surgery at the Oxford Transplant Centre, UK, transplant patients were given low doses of aspirin, which has a some anti-platelet activity. There is risk of bleeding in transplant patients when using anticoagulants like warfarin and herapin. Low dosage of aspirin was used as an alternative. The study concluded that a routine low-dose of aspirin in kidney transplant patients who are also taking ciclosporin significantly reduces the risk of RVT development.

In mostly European experience with 69 patients during 1996-2016, the 5- and 10-year survival rates for SCLS patients were 78% and 69%, respectively, but the survivors received significantly more frequent preventive treatment with IVIG than did non-survivors. Five- and 10-year survival rates in patients treated with IVIG were 91% and 77%, respectively, compared to 47% and 37% in patients not treated with IVIG. Moreover, better identification and management of this condition appears to be resulting in lower mortality and improving survival and quality-of-life results as of late.

Hypercoagulability is an abnormality of the blood that increases the risk of the formation blood clots. Nephrotic syndrome patients have a higher risk of RVT development due to hypercoagulability caused by proteinuria. The increased loss of proteins in the urine caused by nephrotic syndrome results in lower osmotic pressure. Reduced osmotic pressure will trigger the liver to produce more proteins like fibrinogen and beta-thromboglobulin, which promote blood clotting. Other than nephrotic syndrome, there are many other factors that can promote hypercoagulability. Hypercoagulability can be promoted by increased platelet count, enhanced platelet aggregation, increased protein S count, and a decrease in coagulation inhibiters like antithrombin. Hypercoagulability can be inherited and/or acquired. Hyperhomocysteine, a condition known to promote clots, can be caused by a combination of genetic factors and vitamin B6, vitamin b12 and folic acid deficiency. Factor V Leidan and mutations of the prothrombin gene are the two most common genetic causes of hypercoagulability. About 5% of the general population have these heterozygous mutations and in the thrombophilic population, 45–63% have these mutations.

Although the precise molecular cause of SCLS remains undetermined, scientific research in recent years, conducted mainly at a unit (NIAID) of the U.S. National Institutes of Health, has shed some light on its biological and chemical roots. The study of the peripheral microvasculature from patients’ biopsy specimens has not evidenced gross anomalies, disrupted angiogenesis, or inflammatory cells or other factors suggestive of a disorder prone to damage the blood vessels by inflammation. The absence of structural abnormalities is thus consistent with the hypothesis of some kind of defective but curiously reversible cellular phenomenon in the capillaries.

Studies suggest that the presence of various inflammatory factors during episodes of SCLS may explain the temporarily abnormal permeability of the endothelial cells lining the inner surface of the capillaries. These include transient spikes in monocyte- and macrophage-associated inflammatory mediators and temporary increases in the proteins vascular endothelial growth factors (VEGF) and angiopoietin-2. The impairment of endothelial cells in laboratory conditions provoked by serum taken from patients who were having episodes of SCLS is also suggestive of biochemical factors at work.

There is no evidence that SCLS is hereditary, and the role of specific gene defects in patients with SCLS, which might program their endothelial cells for an overreaction to external stimuli, has not been established. The significance, if any, of the paraprotein (MGUS) present in most patients with SCLS is unknown, other than it has been a precursor to multiple myeloma in a minority (7% in the largest reported cohort) of SCLS patients.

It is difficult to determine the incidence of TACO, but its incidence is estimated at about one in every 100 transfusions using active surveillance, and in one in every 10000 transfusions using passive surveillance. TACO is the most commonly reported cause of transfusion-related death and major morbidity in the UK, and second most common cause in the USA.

The risk increases with patients over the age of 60, patients with cardiac or pulmonary failure, renal impairment, hypoalbuminemia or anemia.

Disorders usually resolve after early treatment. If the treatment is delayed, the overall health of the child is improved but physical (reduced) and intellectual (mental disabilities) sequelae are feared. Without treatment or if treatment occurs too late, death is inevitable.

A high risk of death is identified by a brachial perimeter < 11 cm or by a weight-to-height threshold < -3 SD. In practice, malnourished children with edema are suffering from potentially life-threatening severe malnutrition.

In children and some adults, FSGS presents as a nephrotic syndrome, which is characterized by edema (associated with weight gain), hypoalbuminemia (low serum albumin, a protein in the blood), hyperlipidemia and hypertension (high blood pressure). In adults, it may also present as kidney failure and proteinuria, without a full-blown nephrotic syndrome.

There are currently several known genetic causes of the hereditary forms of FSGS.

Some researchers found SuPAR as a cause of FSGS.

Another gene that has been associated with this syndrome is the COL4A5 gene.

Kwashiorkor is a severe form of malnutrition, caused by a deficiency in dietary protein. The extreme lack of protein causes an osmotic imbalance in the gastro-intestinal system causing swelling of the gut diagnosed as an edema or retention of water.

Extreme fluid retention observed in individuals suffering from kwashiorkor is a direct result of irregularities in the lymphatic system and an indication of capillary exchange. The lymphatic system serves three major purposes: fluid recovery, immunity, and lipid absorption. Victims of kwashiorkor commonly exhibit reduced ability to recover fluids, immune system failure, and low lipid absorption, all of which result from a state of severe undernourishment. Fluid recovery in the lymphatic system is accomplished by re-absorption of water and proteins which are then returned to the blood. Compromised fluid recovery results in the characteristic belly distension observed in highly malnourished children.

Capillary exchange between the lymphatic system and the bloodstream is stunted due to the inability of the body to effectively overcome the hydrostatic pressure gradient. Proteins, mainly albumin, are responsible for creating the colloid osmotic pressure (COP) observed in the blood and tissue fluids. The difference in the COP of the blood and tissue is called the oncotic pressure. The oncotic pressure is in direct opposition with the hydrostatic pressure and tends to draw water back into the capillary by osmosis. However, due to the lack of proteins, no substantial pressure gradient can be established to draw fluids from the tissue back into the blood stream. This results in the pooling of fluids, causing the swelling and distention of the abdomen.

The low protein intake leads to some specific signs: edema of the hands and feet, irritability, anorexia, a desquamative rash, hair discolouration, and a large fatty liver. The typical swollen abdomen is due to two causes: ascites because of hypoalbuminemia (low oncotic pressure), and enlarged fatty liver.

Ignorance of nutrition can be a cause. Dr. Michael Latham, former director of the Program in International Nutrition at Cornell University, along with Keith Rosenberg cited a case where parents who fed their child cassava failed to recognize malnutrition because of the edema caused by the syndrome and insisted the child was well-nourished despite the lack of dietary protein.

Protein should be supplied only for anabolic purposes. The catabolic needs should be satisfied with carbohydrate and fat. Protein catabolism involves the urea cycle, which is located in the liver and can easily overwhelm the capacity of an already damaged organ. The resulting liver failure can be fatal. This means in patients suffering from kwashiorkor, protein must be introduced back into the diet gradually. Clinical solutions include weaning the affected with milk products and increasing the intake of proteinaceous material to daily recommended amounts.

Cirrhosis and chronic liver disease were the tenth leading cause of death for men and the twelfth for women in the United States in 2001, killing about 27,000 people each year. The cost of cirrhosis in terms of human suffering, hospital costs, and lost productivity is high. Cirrhosis is more common in men than in women.

Established cirrhosis has a 10-year mortality of 34–66%, largely dependent on the cause of the cirrhosis; alcoholic cirrhosis has a worse prognosis than primary biliary cholangitis and cirrhosis due to hepatitis. The risk of death due to all causes is increased twelvefold; if one excludes the direct consequences of the liver disease, there is still a fivefold increased risk of death in all disease categories.

Hepatocellular carcinoma is a primary liver cancer that is more common in people with cirrhosis. People with known cirrhosis are often screened intermittently for early signs of this tumor, and screening has been shown to improve outcomes.

TACO and TRALI are both respiratory complications following a transfusion. TACO and transfusion related acute lung injury (TRALI) are often difficult to distinguish in the acute situation. TACO is usually associated with hypertension and responds well to diuretics, TRALI is often associated with hypotension and diuretics have a minimal effect.

Affected male and carrier female dogs generally begin to show signs of the disease at two to three months of age, with proteinuria. By three to four months of age, symptoms include for affected male dogs: bodily wasting and loss of weight, proteinuria & hypoalbuminemia. Past nine months of age, hypercholesterolemia may be seen. In the final stages of the disease, at around 15 months of age for affected males, symptoms are reported as being renal failure, hearing loss and death. Since the condition is genetically dominant, diagnosis would also include analysis of the health of the sire and dam of the suspected affected progeny if available.

Samoyed Hereditary Glomerulopathy is caused by a nonsense mutation in codon 1027 of the COL4A5 gene on the X chromosome (glycine to stop codon), which is similar to Alport's syndrome in humans. The disease is simply inherited, X-linked dominant, with males generally having more severe symptoms than females. Clinically, from the age of three to four months, proteinuria in both sexes is seen. In dogs older than this, renal failure in combination with more or less pronounced hearing loss occurs swiftly, and death at the age of 8 to 15 months is expected. In heterozygous females, whereby only one of the two X chromosomes carry the mutation, the disease develops slowly.

The disease is specific to the Samoyed in that, the Samoyed, is the only breed of dog to show the more rapid progression to renal failure and death, as well as affecting males to a much more severe degree than females. The Samoyed, however is not the only breed of dog to suffer from life-threatening renal diseases. Proteinuria has been found consistently in Samoyeds, Doberman Pinschers, and Cocker spaniels.

In humans, the most common causes of EPI are chronic pancreatitis and cystic fibrosis, the former a longstanding inflammation of the pancreas altering the organ's normal structure and function that can arise as a result of malnutrition, heredity, or (in the western world especially), behaviour (alcohol use, smoking), and the latter a recessive hereditary disease most common in Europeans and Ashkenazi Jews where the molecular culprit is an altered, "CFTR"-encoded chloride channel. In children, another common cause is Shwachman-Bodian-Diamond syndrome, a rare autosomal recessive genetic disorder resulting from mutation in the SBDS gene.

When a pleural effusion has been determined to be exudative, additional evaluation is needed to determine its cause, and amylase, glucose, pH and cell counts should be measured.

- Red blood cell counts are elevated in cases of bloody effusions (for example after heart surgery or hemothorax from incomplete evacuation of blood).

- Amylase levels are elevated in cases of esophageal rupture, pancreatic pleural effusion, or cancer.

- Glucose is decreased with cancer, bacterial infections, or rheumatoid pleuritis.

- pH is low in empyema (<7.2) and may be low in cancer.

- If cancer is suspected, the pleural fluid is sent for cytology. If cytology is negative, and cancer is still suspected, either a thoracoscopy, or needle biopsy of the pleura may be performed.

- Gram staining and culture should also be done.

- If tuberculosis is possible, examination for "Mycobacterium tuberculosis" (either a Ziehl–Neelsen or Kinyoun stain, and mycobacterial cultures) should be done. A polymerase chain reaction for tuberculous DNA may be done, or adenosine deaminase or interferon gamma levels may also be checked.

The most common causes of exudative pleural effusions are bacterial pneumonia, cancer (with lung cancer, breast cancer, and lymphoma causing approximately 75% of all malignant pleural effusions), viral infection, and pulmonary embolism.

Another common cause is after heart surgery, when incompletely drained blood can lead to an inflammatory response that causes exudative pleural fluid.

Conditions associated with exudative pleural effusions:

- Parapneumonic effusion due to pneumonia

- Malignancy (either lung cancer or metastases to the pleura from elsewhere)

- Infection (empyema due to bacterial pneumonia)

- Trauma

- Pulmonary infarction

- Pulmonary embolism

- Autoimmune disorders

- Pancreatitis

- Ruptured esophagus (Boerhaave's syndrome)

- Rheumatoid pleurisy

- Drug-induced lupus

The most common causes of transudative pleural effusions in the United States are heart failure and cirrhosis. Nephrotic syndrome, leading to the loss of large amounts of albumin in urine and resultant low albumin levels in the blood and reduced colloid osmotic pressure, is another less common cause of pleural effusion. Pulmonary emboli were once thought to cause transudative effusions, but have been recently shown to be exudative.

The mechanism for the exudative pleural effusion in pulmonary thromboembolism is probably related to increased permeability of the capillaries in the lung, which results from the release of cytokines or inflammatory mediators (e.g. vascular endothelial growth factor) from the platelet-rich blood clots. The excessive interstitial lung fluid traverses the visceral pleura and accumulates in the pleural space.

Conditions associated with transudative pleural effusions include:

- Congestive heart failure

- Liver cirrhosis

- Severe hypoalbuminemia

- Nephrotic syndrome

- Acute atelectasis

- Myxedema

- Peritoneal dialysis

- Meigs' syndrome

- Obstructive uropathy

- End-stage kidney disease

The most reliable test for EPI in dogs and cats is serum trypsin-like immunoreactivity (TLI). A low value indicates EPI. Fecal elastase levels may also be used for diagnosis in dogs.

In dogs, the best treatment is to supplement its food with dried pancreatic extracts. There are commercial preparations available, but chopped bovine pancreas from the butcher can also be used (pork pancreas should not be used because of the rare transmission of pseudorabies). Symptoms usually improve within a few days, but lifelong treatment is required to manage the condition. A rare side-effect of use of dried pancreatic extracts is oral ulceration and bleeding.

Because of malabsorption, serum levels of cyanocobalamin (vitamin B12) and tocopherol (vitamin E) may be low. These may be supplemented, although since cyanocobalamin contains the toxic chemical cyanide, dogs that have serious cobalamin issues should instead be treated with hydroxocobalamin or methylcobalamin. Cyanocobalamin deficiency is very common in cats with EPI because about 99 percent of intrinsic factor (which is required for cyanocobalamin absorption from the intestine) is secreted by the pancreas. In dogs, this figure is about 90 percent, and only about 50 percent of dogs have this deficiency. Cats may suffer from Vitamin K deficiencies. If there is bacterial overgrowth in the intestine, antibiotics should be used, especially if treatment is not working. In dogs failing to gain weight or continuing to show symptoms, modifying the diet to make it low-fiber and highly digestible may help. Despite previous belief that low-fat diets are beneficial in dogs with EPI, more recent studies have shown that a high-fat diet may increase absorption of nutrients and better manage the disease. However, it has been shown that different dogs respond to different dietary modifications, so the best diet must be determined on a case-by-case basis.

One possible sequela, volvulus (mesenteric torsion) is a rare consequence of EPI in dogs.

The disease mechanism (pathophysiology) of RS3PE remains unknown. One study suggested a possible role for vascular endothelial growth factor. A study using magnetic resonance imaging found that tenosynovitis of the extensors of the hands and feet is the major contributor to edema.

The average age of onset is 40 to 60 years, and men are affected more often than women. Adults with Ménétrier disease have a higher risk of developing gastric adenocarcinoma.

RS3PE is a constellation of symptoms that can be caused by many other conditions. Since there is no definitive diagnostic test, other conditions have to be ruled out before this rare condition can be diagnosed.

The main differential diagnosis is polymyalgia rheumatica (PMR), although pain, stiffness and weakness at the level of the shoulders and pelvic girdle with associated systemic symptoms (fever, malaise, fatigue, weight loss) is more typical of PMR. Prospective studies have found a subgroup of PMR patients with hand edema, as well as other similarities. Thus, RS3PE has been proposed as a condition related to PMR or even that they are both part of the same disorder. However, PMR typically requires protracted courses of steroids, whereas corticosteroids can be tapered more quickly with persisting remission in RS3PE.

Other rheumatological disorders that can cause the features typical for RS3PE include late onset (seronegative) rheumatoid arthritis, acute sarcoidosis, ankylosing spondylitis and other spondyloarthropathies such as psoriatic arthropathy, mixed connective tissue disease, chondrocalcinosis and arthropathy due to amyloidosis.

RS3PE has been documented in patients with cancers (Non-Hodgkin's lymphoma, gastric cancer, pancreatic cancer, lung cancer, breast cancer, colon cancer, prostate cancer and bladder cancer, among others), in whom it might represent a paraneoplastic manifestation.

Other underlying disorders include vasculitides such as polyarteritis nodosa.

Other causes of edema include heart failure, hypoalbuminemia, nephrotic syndrome and venous stasis. The key distinguishing feature is that these conditions don't tend to manifest with pitting edema at the back of the hands.

Leukonychia (or leuconychia), also known as white nails or milk spots, is a medical term for white discolouration appearing on nails. It is derived from the Greek words "leuko" ("white") and "nychia" ("nails"). The most common cause is injury to the base of the nail (the matrix) where the nail is formed.

It is harmless and most commonly caused by minor injuries, such as nail biting, that occur while the nail is growing. Leukonychia occurs most commonly in healthy individuals, unrelated to any known nutritional or physiological deficiency. When caused by injury the marks will disappear as the nail grows outwards, however a dietary deficiency will cause recurrent leukonychia.

Other possible reasons for this problem with nail colour can be linked to:

- Arsenic poisoning

- Lead poisoning

- Pneumonia

- Heart disease

- Renal failure

- Ill health

- Hypoalbuminemia

- Vitamin deficiency

- Ulcerative colitis

- Hepatic cirrhosis

- Psychogenic stresses

- Onychophagia

- Occupational trauma

- Zinc deficiency

- Protein deficiency

- Psoriasis as well as eczema

- Iron deficiency