Minerals Calcium, Phosphorus & Magnesium PDF

MLT 304 Minerals Calcium, phosphorus & magnesium SEC 2 1|Page  A healthy person’s body contains approximately 1.0 to 1.3 kg Ca; 99 % is found in the bones and teeth, 1 % in soft tissues, and 0.1 % in extracellular space. Calcium exists...

MLT 304 Minerals Calcium, phosphorus & magnesium SEC 2 1|Page  A healthy person’s body contains approximately 1.0 to 1.3 kg Ca; 99 % is found in the bones and teeth, 1 % in soft tissues, and 0.1 % in extracellular space. Calcium exists in plasma in three forms: 50% free (ionized), 40% bound to protein, 10% bound to anions. It is the free form of calcium that is biologically active. Ca concentration is greatly affected by 2 factors: a- Albumin concentration. The albumin level affects the overall Ca level in plasma. Patients with hypoalbuminemia (↓ albumin) have lower overall calcium concentrations but the ionized, biologically active fraction is usually normal. This is relatively common cause of hypocalcemia in patients without clinical symptoms. How are calcium levels corrected in patients with hypocalcemia and low serum albumin levels? Corrected calcium (mg/dl) = total calcium (mg/dl) + 0.8 (4 – serum albumin (g/dl)) Where 4 represented the average albumin level. b- Changes in pH Acidosis reduces the calcium bond to albumin and increases the ionized calcium fraction. while alkalosis reduces the ionized calcium fraction and invokes clinical symptoms connected to hypocalcemia. 2|Page Use: Diagnosis and monitoring of a wide range of disorders, including disorders of protein and vitamin D, and diseases of the bone, kidney, parathyroid gland, or GI tract. Reference Values Clinical significance: a. Hypercalcemia is caused by primary hyperparathyroidism, other endocrine disorders such as hypothyroidism and acute adrenal insufficiency, malignancy involving bone, and renal failure. b. Hypocalcemia is caused by hypoparathyroidism, hypoalbuminemia, chronic renal failure, magnesium deficiency, and vitamin D deficiency. 3|Page Sample type and precautions: 1- The preferred specimen for total Ca2+ determinations is either serum or lithium heparin plasma collected without venous stasis. Because anticoagulants such as EDTA or oxalate bind Ca2+ tightly and interfere with measurement, they are unacceptable for use. 2- The proper collection of samples for ionized Ca2+ measurements require greater care. Because loss of CO2 will increase pH, samples must be collected anaerobically. Although heparinized whole blood is the preferred sample, serum from sealed evacuated blood collection tubes may be used if clotting and centrifugation are done quickly (