HIV wasting syndrome is a rare condition defined by a loss of weight by at least 10 percent accompanied by diarrhea, chronic weakness and documented fevers lasting for up to a month which can only be accounted for by the human immunodeficiency virus infection. The decrease in fat and lean body mass are responsible for the weight loss.
HIV wasting syndrome (HIV WS) is characterized by a minimum of 10 percent weight loss which is accompanied by severe diarrhea, chronic weakness and fever lasting for more than three to four weeks and which can only be accounted for by the human immunodeficiency virus (HIV) infection . The weight loss in HIV patients can be acute due to infections or can be gradual due to malabsorption. In HIV WS, the loss of weight is due to a decrease in fat as well as lean body mass irrespective of whether the patient is on treatment with anti-retroviral medications, viral loads, and T-cell counts .
Initially, the patient's weight loss is not noticed as wasting although the patient's body composition has begun to change with the patient manifesting clinical features of malnutrition e.g. increase in the extracellular mass to body composition monitoring (BCM) ratio . Failure to exercise may lead to loss of muscle mass in the early stages of HIV infection but its cause in the penultimate stages is still unknown. In HIV patients with diabetes, the protein and muscle mass loss may be even more severe.
Clinically, HIV WS manifests differently amongst men compared to women infected with HIV. In men with HIV WS, there is asthenia with a gradually progressive loss of weight, diminished metabolism and fat sparing versus an excessive decrease in lean body mass (LBM). On the other hand, women have an excessive decrease in body fat compared to LBM and lose more muscle mass in the late stages of the disease .
Patients with HIV WS may have concomitant myopathies such as polymyositis or polyarteritis nodosa (PAN) which can confuse the clinical picture. In addition, antiretroviral treatment with zidovudine can also cause myopathy which does not improve even after cessation of the medication .
The workup of HIV WS should be able to identify the condition and exclude other causes of weight loss such as malnutrition, malabsorption, and infections in patients with HIV. It is also important to differentiate it from HIV-lipodystrophy, and hyperlactatemia which can occur with nucleoside analog reverse transcriptase inhibitor (NRTI) therapy . Besides history and physical examination, the workup should include nutritional assessment, serial measurements of weight in standardized conditions  to detect and monitor wasting; body mass index (BMI) measurement, weight trends to monitor the patient's nutritional status, bioimpedance analysis over a period of time to evaluate LBM, total body water and fat using regression analysis  and sequential anthropometry (mid arm circumference, triceps skinfold thickness) to predict prognosis .
An endocrine evaluation to exclude hypogonadism as the cause of wasting and gastrointestinal referral to look for malabsorption are also a vital part of the workup.
Dual-energy X-ray absorptiometry (DEXA), magnetic resonance imaging (MRI), and computed tomography (CT) can provide more accurate information about body composition but are expensive tests and therefore are only being used currently for research purposes.