Re: Is a hypercalcemia can not be detected in a blood test?

There is an excellent resource at:
http://www.ncbi.nlm.nih.gov/books/NBK250/

Goldstein DA. Chapter 143: Serum Calcium. In: Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Walker HK, Hall WD, Hurst JW, editors. Boston: Butterworths; 1990.

From that chapter:
"The measurement of serum calcium is fraught with possible errors. Several means of contamination might lead to false elevations of serum calcium concentration. Falsely low levels are less common, so if several measurements are obtained, the lowest is usually the most accurate. The precision of the SMAC analysis, an automated colorimetric technique, is usually equal or superior to that of manual analysis. Nevertheless, falsely high or low values may be obtained in patients with liver or renal failure or in patients with lipemic or hemolyzed specimens. Venous occlusion of the arm during venipuncture may increase the total concentration of serum calcium by up to 0.3 mmol/L. This results from an increase in plasma protein concentration caused by hemodynamic changes. Another source of error is posture. If the patient stands up from a supine position, there may be an increase of 0.05 to 0.20 mmol/L in serum calcium. Still another possible source of error is hemolysis. Some methods of measuring calcium are affected by high levels of hemoglobin, and red cells may take up calcium after prolonged contact. If an error is suspected and the measurement is to be redone, the blood should be drawn following an overnight fast because the daily intake of calcium may contribute to the serum calcium concentration as much as 0.15 mmol/L."