Laboratory Studies
Clinical suspicion of the underlying disease process should guide appropriate laboratory studies, some of which are as follows:
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Malnutrition: Lymphocyte count and blood urea nitrogen levels are decreased. Transferrin, prealbumin, and retinol-binding protein have shorter half-lives compared with albumin and better reflect short-term changes in nutritional status than albumin, which has a long half-life.
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Inflammation: C-reactive protein levels and increased erythrocyte sedimentation rate are elevated.
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Nephrotic syndrome: The 24-hour urine collection contains more than 3 g of protein in 24 hours.
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Cirrhosis: Liver function test findings (transaminase levels) may be elevated or normal in patients who are cirrhotic. Coagulation studies may be abnormal. Cirrhosis has numerous potential etiologies, and more specific studies, such as hepatitis screening, may be needed.
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Malabsorption: Fecal fat studies including Sudan qualitative stain for fat, 72-hour quantitative fecal fat collection, and fecal a-1-antitrypsin clearance are needed.
Serum protein electrophoresis results help to determine if hypergammaglobulinemia is present.
None of the various correction factors for determining the effects of hypoalbuminemia on the plasma calcium concentration has proven reliable. Corrected calcium (mg/dL) is equal to measured total calcium (mg/dL) plus 0.8 (average normal albumin level of 4.4 minus serum albumin [g/dL]). The only method of identifying true (ionized) hypocalcemia in the presence of hypoalbuminemia is to measure the ionized fraction directly.
Elderly patients living in nursing homes or other institutionalized settings who have hypoalbuminemia should be evaluated for treatable comorbid conditions contributing to the malnutrition (eg, medications causing decreased appetite, thyroid dysfunction, diabetes, malabsorption, depression, cognitive impairment).
Imaging Studies
Imaging studies can be performed for the following:
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Liver ultrasound for evidence of cirrhosis
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Small bowel barium series for mucosal abnormalities typical of malabsorption syndromes
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Imaging studies as appropriate to seek infectious causes of inflammation and hypoalbuminemia (eg, chest radiography)
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Echocardiogram for congestive heart failure
Procedures
Procedures can be performed for the following:
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Liver biopsy to confirm cirrhosis
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Kidney biopsy to help evaluate etiology of nephrosis
Histologic Findings
When hypoalbuminemia is due to cirrhosis, liver biopsy findings show a loss of hepatic architecture, fibrosis, and nodular regeneration. The pattern of injury and special stains can help determine the etiology of cirrhosis.
When hypoalbuminemia is due to nephrotic syndrome secondary to a primary renal disorder, light microscopy may show sclerosis (focal glomerulosclerosis), mesangial immunoglobulin A (immunoglobulin A nephropathy), or no changes (minimal change disease). Electron microscopy may show subepithelial immunoglobulin G deposits (membranous glomerulonephritis).
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Albumin.
