In a full nutritional assessment it can be useful to screen the following biochemical parameters: albumin, prealbumin, CRP, transferrin, hemoglobin, urea and creatine, lymphocytes and point deficiencies.
As a measure in a nutritional assessment, albumin is useful because a fast diminishing albumin concentration is a sign for an inflammatory reaction. An increasing albumin level can be interpreted as an improvement; the patient becomes anabolic. The albumin level only increases when the inflammation decreases. Nutrition has no influence on that.
In certain cases creatinine can be used to get an impression of the quantity of muscle mass. When the kidney works well, a decreased creatinine can indicate decreased muscle mass. Creatinine arises by the conversion of creatine to creatinine in the muscle mass.
An increased CRP is a result of inflammation. CRP can increase up to a thousand times as a reaction to inflammation, sepsis or infection. It can be used to monitor stressresponse during the acute fase.
Hemoglobin: This parameter can be used to determine the response to illness. During illness Hb decreases very fast.
The total lymphocytes count is not a sensitive index for malnutrition, because it reacts very slowly to recovery from malnutrition. The total amount of lymphocytes can increase in case of inflammation, radiation therapy and chemotherapy.
Point deficiencies: Screening on point deficiencies with the aid of medical and food questionnaires. Only in case of severe deficiencies this is shown in the blood.
This is a sensitive indicator for protein-deficiency. Prealbumin increases with nutritional therapy, even when the disease condition is not getting better. It decreases fast in case of a low energy intake, even if protein intake is adequate. However it also decreases in case of inflammation and is dependent on the level of hydration. Careful interpretation of prealbumin values in the clinical setting is advised.
Transferrin is produced in the liver. It is a transport protein for iron and zinc, and can also be used as an indicator for the iron status in the body. In iron-deficiency, the serum transferrin increases. In illness, transferrin is low because the liver produces less transferrin. Anaemia and nephrosis also influence transferrin.
The liver produces urea if amino acids break down. The urea production is more after a protein rich meal and when endogenous catabolism is increased (in case of infections, internal bleedings, intoxication, fever and after tissue damage).
More information on these biochemical parameters can be found in this document.