Albumin, serum nitrogen content

Blood and urine samples are often collected after the patient has fasted for a period of time (e.g., overnight), particularly for cholesterol or glucose analysis. One study indicates that an average breakfast has no significant effect on the concentration of the blood content of carbon dioxide, chloride, sodium, potassium, calcium, urea nitrogen, uric acid, creatinine, total protein, and albumin. Serum phosphorus is slighdy depressed at 45 min after the meal but not after 2 h. 

The biuret method The bimet method is a colorimetric technique specific for proteins and peptides. Copper salts in alkaline solution form a pruple complex with substances containing two or more peptide bonds. The absorbance produced is proportional to the number of peptide bonds that are reacting and therefore to the number of protein molecules present in the reaction system. Thus, the biuret reaction with proteins is suitable for the determination of total protein by spectrophotometry (at 540-560 nm). The method is used extensively in clinical laboratories, particularly in automated analyzers in which protein concentration can be measured down to 0.1-0.15gl. The use of bovine or human serum albumin to standardize the biuret method is well established. ITigh-purity albumin contains only amino acids its nitrogen content is a constant fraction... 

Various etiologies produce differing biochemical pictures. " Determination of serum content of calcium (albumin corrected), phosphorus, alkaline phosphatase, urea nitrogen, creatinine, PTH, 25(OH) vitamin D, and calcitriol, as well as urinary calcium, creatinine, and phosphorus, can help in determining the cause, deciding on treatment, and monitoring efficacy of therapy. Definitive diagnosis is by bone biopsy. 

At least two symptoms are related to the increased protein breakdown observed in diabetes (1) the increased amount of nitrogen in the urine, especially during periods of acidosis (when total nitrogen excretion per day reaches 15-25 g) and (2) a drop in protein content of the body in general, and a reduced concentration in serum albumin in particular. 

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