Hypoproteinemia

Hypoproteinemia is an abnormally low level of circulating plasma proteins. It is usually diagnosed by a low total serum protein or, more commonly, by a low serum albumin concentration. Hypoalbuminemia, a common form of hypoproteinemia, can contribute significantly to edema due to reduced oncotic pressure.

Causes of hypoproteinemia are diverse. Decreased hepatic synthesis occurs in liver disease (cirrhosis, hepatitis) and in severe malnutrition or cachexia. Increased loss of protein happens in nephrotic syndrome, protein-losing enteropathy, extensive burns, and certain gastrointestinal or urinary disorders. Increased catabolic rate due to systemic inflammation, infection, or trauma can also lower protein levels. Poor intake or absorption of protein, malnutrition, malabsorption syndromes, and severe burns are additional contributing factors. Dilution from fluid overload or aggressive IV fluids may transiently lower measured protein levels.

Pathophysiology centers on the balance of protein production, loss, and distribution. Low albumin lowers plasma oncotic pressure, promoting fluid movement into interstitial spaces and causing edema and ascites. Chronic hypoproteinemia can impair wound healing, immune function, and drug pharmacokinetics. In specific diseases, such as cirrhosis or nephrotic syndrome, the protein imbalance reflects ongoing organ pathology and systemic effects.

Clinical assessment involves recognizing edema, ascites, or poor wound healing, accompanied by low serum albumin and/or low total protein. Evaluation typically includes liver function tests, renal function, urinalysis for proteinuria, nutritional assessment, and targeted testing to identify underlying causes (e.g., imaging for liver disease, stool studies for malabsorption).

Management focuses on treating the underlying cause and supporting nutrition. Goals include adequate protein intake, correction of nutritional deficiencies, and management of edema or effusions with appropriate therapies. In selected cases, albumin infusions may be used short term; however, long-term benefit is primarily achieved by treating the underlying disease. Prognosis depends on the etiology and the severity of associated organ dysfunction.