The current gold standard diagnostic test for EE is intestinal biopsy and histological analysis. Histological changes observed include:

- Villous blunting

- Crypt hypertrophy

- Villous fusion

- Mucosal inflammation

However, this procedure is considered too invasive, complex and expensive to be implemented as standard of care. As a result, there are various research efforts underway to identify biomarkers associated with EE, which could serve as less invasive, yet representative, tools to screen for and identify EE from stool samples.

In an effort to identify simple, accurate diagnostic tests for EE, the Bill and Melinda Gates Foundation (BMGF) has established an EE biomarkers consortium as part of their Global Grand Challenges initiative (specifically, the Discover Biomarkers of Gut Function challenge).

So far, various biomarkers have been selected and studied based on the current understanding of EE pathophysiology:

- Gut permeability/barrier function

- Dual sugar permeability (lactose-to-mannitol ratio)

- Intestinal inflammation

- Alpha-1 anti-trypsin

- Neopterin

- Myeloperoxidase

- Exocrine (hormonal) markers

- Bacterial translocation markers

- Endotoxin core antibody

- Markers of systemic inflammation

- Alpha-1 glycoprotein

- C-reactive protein (CRP)

It is postulated that the limited of understanding of EE is partially due to the paucity of reliable biomarkers, making it difficult for researchers to track the epidemiology of the condition and assess the efficacy of interventions.

There are multiple large-field, multi-country research initiatives focusing on strategies to prevent and treat EE.

- The MAL-ED project

- The Alive and Thrive nutrition project

- The Sanitation, Hygiene and Infant Nutrition Efficacy (SHINE) Trial (ClinicalTrials.gov identifier: NCT01824940)

- The WASH Benefits Study

An examination reveals massive fluid retention and generalized swelling. Abnormal sounds are heard when listening to the heart and lungs with a stethoscope. Blood pressure may be high. The patient may have signs of malnutrition.

A urinalysis reveals large amounts of protein and the presence of fat in the urine. Total protein in the blood may be low. The disorder can be screened during pregnancy by finding elevated levels of alpha-fetoprotein on a routine sampling of amniotic fluid. Genetic tests should be used to confirm the diagnosis, if the screening test is positive.

CNF is one of the Finnish heritage diseases. By use of positional cloning strategies, Kestila et al. isolated the gene responsible for NPHS1. Mutations in Finnish patients with NPHS1 were found in this gene, which they termed nephrin. The most common Finnish mutation was a deletion of 2 nucleotides in exon 2 (602716.0001), resulting in a frameshift and a truncated protein. The predicted nephrin protein belongs to the immunoglobulin family of cell adhesion molecules and is specifically expressed in renal glomeruli. It was also observed that, in most cases, alleles typically found on CNF chromosomes of Finnish families were also found on CNF chromosomes of non-Finnish families from North America and Europe.

Frequent infections may occur over the course of the disease.

Marchiafava-Bignami disease is routinely diagnosed with the use of an MRI due to the fact that the majority of clinical symptoms are non-specific. Before the use of such imaging equipment, it was unable to be diagnosed until autopsy. The patient usually has a history of alcoholism or malnutrition and neurological symptoms are sometimes present and can help lead to a diagnosis. MBD can be told apart from other neural diseases due to the symmetry of the lesions in the corpus callosum as well as the fact that these lesions don’t affect the upper and lower edges.

There are two clinical subtypes of MBD

Type A- Stupor and coma predominate. Radiological imaging shows involvement of the entire corpus callosum. This type is also associated with symptoms of the upper motor neurons.

Type B- This type has normal or only mildly impair mental status and radiological imaging shows partial lesions in the corpus callosum.

Measurements of a child’s growth provide the key information for the presence of malnutrition, but weight and height measurements alone can lead to failure to recognize kwashiorkor and an underestimation of the severity of malnutrition in children.

Antiretrovirals and anabolic steroids have been used to treat HIV wasting syndrome. Additionally, an increase in protein-rich foods such as peanut butter, eggs, and cheese can assist in controlling the loss of muscle mass.

Feline hepatic lipidosis shares similar symptoms to other problems, including liver disease, renal failure, feline leukemia, Feline infectious peritonitis and some cancers. Diagnosis requires tests that target the liver to make an accurate diagnosis. Jaundice is highly indicative of the disease. Blood tests and a liver biopsy will confirm the presence of the disease.

Physical examination to examine muscle wasting, laboratory investigations.

A large percentage of children that suffer from PEM also have other co-morbid conditions. The most common co-morbidities are diarrhea (72.2% of a sample of 66 subjects) and malaria (43.3%). However, a variety of other conditions have been observed with PEM, including sepsis, severe anaemia, bronchopneumonia, HIV, tuberculosis, scabies, chronic suppurative otitis media, rickets, and keratomalacia. These co-morbidities tax already malnourished children and may prolong hospital stays initially for PEM and may increase the likelihood of death.

Although protein energy malnutrition is more common in low-income countries, children from higher-income countries are also affected, including children from large urban areas in low socioeconomic neighborhoods. This may also occur in children with chronic diseases, and children who are institutionalized or hospitalized for a different diagnosis. Risk factors include a primary diagnosis of intellectual disability, cystic fibrosis, malignancy, cardiovascular disease, end stage renal disease, oncologic disease, genetic disease, neurological disease, multiple diagnoses, or prolonged hospitalization. In these conditions, the challenging nutritional management may get overlooked and underestimated, resulting in an impairment of the chances for recovery and the worsening of the situation.

PEM is fairly common worldwide in both children and adults and accounts for 6 million deaths annually. In the industrialized world, PEM is predominantly seen in hospitals, is associated with disease, or is often found in the elderly.

However, diagnosis can be difficult due to the comprehensive measurements used in research that are not always practical in healthcare settings. Hand grip strength alone has also been advocated as a clinical marker of sarcopenia that is simple and cost effective and has good predictive power, although it does not provide comprehensive information.

Exercise remains the intervention of choice for sarcopenia but translation of findings into clinical practice is challenging. The type, duration and intensity of exercise are variable between studies, so an ‘off the shelf’ exercise prescription for sarcopenia remains an aspiration.

The role of nutrition in preventing and treating sarcopenia is less clear. Large, well-designed studies of nutrition particularly in combination with exercise are needed, ideally across healthcare settings. For now, basing nutritional guidance on the evidence available from the wider health context is probably the best approach with little contention in the goals of replacing vitamin D where deficient, and ensuring an adequate intake of calories and protein, although there is debate about whether currently recommended protein intake levels are optimal.

A working definition for diagnosis was proposed in 1998 by Baumgartner "et al" which uses a measure of lean body mass as determined by dual energy X-ray absorptiometry (DEXA) compared to a normal reference population. His working definition uses a cut point of 2 standard deviations below the mean of lean mass for gender specific healthy young adults.

Since Baumgartner's working definition first appeared, some consensus groups have refined the definition, including the European Working Group on Sarcopenia in Older People (EWGSOP). Their consensus definition is:

- Low muscle mass, (e.g. >2 standard deviations below that mean measured in young adults [aged 18–39 years in the 3rd NHANES population] of the same sex and ethnic background).

And either:

- Low gait speed (e.g. a walking speed below 0.8 m/s in the 4-m walking test)

Or:

- Low muscular strength (e.g. grip strength: <30 kg in males, <20 kg in females)

Severe sarcopenia requires the presence of all three conditions.

According to the 2007 AHRQ National Inpatient Sample, in a projected 129,164 hospital encounters in the United States, cachexia was listed as at least one of up to 14 recorded diagnosis codes based on a sample of 26,325 unweighted encounters. A sample of 32,778 unweighted US outpatient visits collected by the CDC's National Ambulatory Medical Care Survey did not list any visits where cachexia was one of up to three recorded diagnoses treated during the visit.

Growth stunting is identified by comparing measurements of children's heights to the World Health Organization 2006 growth reference population: children who fall below the fifth percentile of the reference population in height for age are defined as stunted, regardless of the reason. The lower than fifth percentile corresponds to less than two standard deviations of the WHO Child Growth Standards median.

As an indicator of nutritional status, comparisons of children's measurements with growth reference curves may be used differently for populations of children than for individual children. The fact that an individual child falls below the fifth percentile for height for age on a growth reference curve may reflect normal variation in growth within a population: the individual child may be short simply because both parents carried genes for shortness and not because of inadequate nutrition. However, if substantially more than 5% of an identified child population have height for age that is less than the fifth percentile on the reference curve, then the population is said to have a higher-than-expected prevalence of stunting, and malnutrition is generally the first cause considered.

The prognosis for tropical sprue may be excellent after treatment. It usually does not recur in people who get it during travel to affected regions. The recurrence rate for natives is about 20%, but another study showed changes can persist for several years.

There is no single, specific test for malabsorption. As for most medical conditions, investigation is guided by symptoms and signs. A range of different conditions can produce malabsorption and it is necessary to look for each of these specifically. Many tests have been advocated, and some, such as tests for pancreatic function are complex, vary between centers and have not been widely adopted. However, better tests have become available with greater ease of use, better sensitivity and specificity for the causative conditions. Tests are also needed to detect the systemic effects of deficiency of the malabsorbed nutrients (such as anaemia with vitamin B12 malabsorption).

Preventive measures for visitors to tropical areas where the condition exists include steps to reduce the likelihood of gastroenteritis. These may comprise using only bottled water for drinking, brushing teeth, and washing food, and avoiding fruits washed with tap water (or consuming only peeled fruits, such as bananas and oranges). Basic sanitation is necessary to reduce fecal-oral contamination and the impact of environmental enteropathy in the developing world.

Three main things are needed to reduce stunting:

- a kind of environment where political commitment can thrive (also called an "enabling environment")

- applying several nutritional modifications or changes in a population on a large scale which have a high benefit and a low cost

- a strong foundation that can drive change (food security, empowerment of women and a supportive health environment through increasing access to safe water and sanitation).

To prevent stunting, it is not just a matter of providing better nutrition but also access to clean water, improved sanitation (hygienic toilets) and hand washing at critical times (summarised as "WASH"). Without provision of toilets, prevention of tropical intestinal diseases, which may affect almost all children in the developing world and lead to stunting will not be possible.

Studies have looked at ranking the underlying determinants in terms of their potency in reducing child stunting and found in the order of potency:

- percent of dietary energy from non-staples (greatest impact)

- access to sanitation and women's education

- access to safe water

- women's empowerment as measured by the female-to-male life expectancy ratio

- per capita dietary energy supply

Three of these determinants should receive attention in particular: access to sanitation, diversity of calorie sources from food supplies, and women's empowerment. A study by the Institute of Development Studies has stressed that: "The first two should be prioritized because they have strong impacts yet are farthest below their desired levels".

The goal of UN agencies, governments and NGO is now to optimise nutrition during the first 1000 days of a child's life, from pregnancy to the child's second birthday, in order to reduce the prevalence of stunting. The first 1000 days in a child's life are a crucial "window of opportunity" because the brain develops rapidly, laying the foundation for future cognitive and social ability. Furthermore, it is also the time when young children are the most at risk of infections that lead to diarrhoea. It is the time when they stop breast feeding (weaning process), begin to crawl, put things in their mouths and become exposed to faecal matter from open defecation and environmental enteropathies.

Treatment is variable depending on individuals. Some treatments work extremely well with some patients and not at all with others. Some treatments include Therapy with thiamine and vitamin B complex. Alcohol consumption should be stopped. Some patients survive, but with residual brain damage and dementia. Others remain in comas that eventually lead to death. Nutritional counseling is also recommended. Treatment is often similar to those administered for Wenicke-Korsakoff syndrome or for alcoholism.

Type A has 21% mortality rate and an 81% long-term disability rate. Type B has a 0% mortality rate and a 19% long-term disability rate.

Early and aggressive treatment is required to control the disorder. Diuretic medications help rid the body of excess fluid. ACE inhibitor medications (like Captopril and others) and non-steroidal anti-inflammatory drugs (like indomethacin) are used to slow the spilling of protein (albumin) in the urine. Antibiotics may be needed to control infections. Patients may also take iron supplements, potassium chloride, thyroxine and other vitamins to replenish what minerals the kidneys have leaked out.

Most patients will undergo regular and frequent albumin infusion (often daily) to replace what kidneys have lost. Infusions are performed via IV so a central venous catheter will need to be surgically inserted into patients chest or groin.

Dietary modifications may include the restriction of sodium and use of dietary supplements as appropriate for the nature and extent of malnutrition. Fluids may be restricted to help control swelling.

Many patients have a gastrostomy tube (g-tube) inserted for medication and/or feeds. Some patients develop oral aversions and will use the tube for all feeds. Other patients eat well and only use the tube for medicine or supplemental feeds. The tube is also useful for patients needing to drink large amounts of fluids around the time of transplant.

Patient will require removal of the kidneys (one at the time or both), dialysis, and ultimately a kidney transplant.

Measures have been taken to reduce child malnutrition. Studies for the World Bank found that, from 1970 to 2000, the number of malnourished children decreased by 20 percent in developing countries. Iodine supplement trials in pregnant women have been shown to reduce offspring deaths during infancy and early childhood by 29 percent. However, universal salt iodization has largely replaced this intervention.

The Progresa program in Mexico combined conditional cash transfers with nutritional education and micronutrient-fortified food supplements; this resulted in a 10 percent reduction the prevalence of stunting in children 12–36 months old. Milk fortified with zinc and iron reduced the incidence of diarrhea by 18 percent in a study in India.

Untreated, the disease has a mortality rate upwards of 90%. Cats treated in the early stages can have a recovery rate of 80–90%. Left untreated, the cats usually die from severe malnutrition or complications from liver failure. Treatment usually involves aggressive feeding through one of several methods.

Cats can have a feeding tube inserted by a veterinarian so that the owner can feed the cat a liquid diet several times a day. They can also be force-fed through the mouth with a syringe. If the cat stops vomiting and regains its appetite, it can be fed in a food dish normally. The key is aggressive feeding so the body stops converting fat in the liver. The cat liver has a high regeneration rate and the disease will eventually reverse assuming that irreparable damage has not been done to the liver.

The best method to combat feline hepatic lipidosis is prevention and early detection. Obesity increases the chances of onset. In addition, if a cat stops eating for 1–2 days, it should be taken to a vet immediately. The longer the disease goes untreated, the higher the mortality rate.

Malnutrition–inflammation complex (syndrome), abbreviated as "MICS" and also known as "malnutrition–inflammation–cachexia syndrome", is a common condition in chronic disease states such as chronic kidney disease (where it is also known as uremic malnutrition or protein–energy malnutrition) and chronic heart failure.

The MICS is believed to be a cause of survival paradoxes seen in these distinct patient populations, also known as reverse epidemiology populations.

The treatment or management of cachexia depends on the underlying causes, the general prognosis and other person related factors. Reversible causes, underlying diseases and contributing factors are treated if possible and acceptable. A growing body of evidence supports the efficacy of (HMB) as a treatment for reducing, or even reversing, the loss of muscle mass, muscle function, and muscle strength that occurs in hypercatabolic disease states such as cachexia; consequently, it is recommended that both the prevention and treatment of muscle wasting conditions include supplementation with HMB, regular resistance exercise, and consumption of a high-protein diet. Progestins such as megestrol acetate are a treatment option in refractory cachexia with anorexia as a major symptom.

Cachexia occurs less frequently now in HIV/AIDS than in the past due to the advent of highly active antiretroviral therapy (HAART). Treatment involving different combinations for cancer cachexia is recommended in Europe, as a combination of nutrition, medication and non-drug-treatment may be more effective than monotherapy. Non-drug therapies which have been shown to be effective in cancer induced cachexia include nutritional counselling, psychotherapeutic interventions, and physical training. Anabolic-androgenic steroids like oxandrolone may be beneficial in cancer cachexia but their use is recommended for maximal 2 weeks since a longer duration of treatment increases the burden from side effects.

Other drugs that have been used or are being investigated in cachexia therapy, but which lack conclusive evidence of efficacy or safety, and are not generally recommended include:

- Thalidomide and cytokine antagonists

- Cannabinoids

- Omega-3 fatty acids, including eicosapentaenoic acid (EPA)

- Non-steroidal anti-inflammatory drugs

- Prokinetics

- Ghrelin and ghrelin receptor agonist

- Anabolic catabolic transforming agents such as MT-102

- Selective androgen receptor modulators

- Cyproheptadine

- Hydrazine

Medical marijuana has been allowed for the treatment of cachexia in some US states, such as Illinois, Maryland, Delaware, Nevada, Michigan, Washington, Oregon, California, Colorado, New Mexico, Arizona, Vermont, New Jersey, Rhode Island, Maine, and New York Hawaii and Connecticut.

There is insufficient evidence to support the use of oral fish oil for the management of cachexia associated with advanced cancer.

Treatment is primarily through diet. Dietary fiber and fat can be increased and fluid intake, especially fruit juice intake, decreased. With these considerations, the patient should consume a normal balanced diet to avoid malnutrition or growth restriction. Medications such as loperamide should not be used. Studies have shown that certain probiotic preparations such as "Lactobacillus rhamnosus" (a bacterium) and "Saccharomyces boulardii" (a yeast) may be effective at reducing symptoms.