Malnutrition

A number of laboratory studies have been used in the nutritional assessment of malnutrition; however, they are unlikely to uncover marginal malnutrition. Although plasma or serum albumin is a popular measure, sick patients may have low levels for several other reasons, such as inflammatory processes, gut losses due to gastrointestinal or cardiac disease, and renal losses due to kidney disease. Moreover, even when malnutrition is chronic, this measure is often normal because of compensatory mechanisms. Typical laboratory findings include serum albumin of less than 3.5 g/dL, serum prealbumin concentration less than 10 mg/dL, total lymphocyte count less than 1,200 mm3, and an anemia of chronic disease. (1)

Since measuring gastric acidity directly by gastric intubation is uncomfortable for the patient, other methods have been devised. Analysis can be done using the Heidelberger pH capsule gastrointestinal radio transmitter or even with a simple, inexpensive gelatin capsule containing specially treated cotton floss*.

Even when it is absent in the fasting state, acid production following the entry of food is often normal; thus testing must be performed after the patient is given a potent parietal cell stimulus. (2)

Basal serum gastrin measurement may also be helpful, as somewhat increased levels can be found in conditions associated with achlorhydria if the antrum is not severely affected–such as atrophic gastritis and pernicious anemia. (3)

Specific Nutrient Abnormalities

Calcium

Ionized calcium measures unbound serum calcium. It is a useful measure of calcium balance when it is low; however, normal levels do not rule out a negative calcium balance. (4)

Hair calcium must be interpreted with caution, as a negative calcium balance may be accompanied by elevated hair levels. (This combination suggests that possibility of a nutritionally-induced secondary hyperparathyroidism related to a low calcium, high phosphorus diet.) (5) Moreover, grey hair is naturally lower in calcium. (6)