Urine calcium measurement is used to assess the risk of kidney stones from calcium oxalate and phosphate as well as to evaluate bone diseases, including osteoporosis.
Calcium (Ca) plays an important role in muscle contraction, cardiac function, the transmission of nerve impulses, and blood clotting. The amount of calcium in the blood is about 1-2% of the total, while the rest 98-99% is in the teeth and bones. Bone storage provides an excellent reservoir that is readily available for release into the bloodstream, maintaining a normal blood calcium level. There is an inverse relationship between calcium and phosphorus: as the serum calcium concentration increases, the phosphorus concentration decreases.
Two hormones work together to control blood calcium levels. Calcitonin (CT), which is secreted by the thyroid gland and causes kidney calcium excretion, results in a decrease in blood calcium and parathyroid hormone (PTH) which directly acts to the bones in order to release calcium in the blood when needed and also increases the absorption of calcium from the intestine and kidneys.
Most of the calcium lost from the body is excreted in the feces. 99% of the kidney-filtered calcium is reabsorbed. Whenever there are elevated levels of calcium in the urine, it is usually the result of elevated serum calcium concentrations. Urine calcium is mainly used to evaluate the function of parathyroid glands and to evaluate vitamin D therapy.
Possible Interpretations of Pathological Values
- Increase: Breast cancer, Cushing's syndrome, Fanconi's syndrome, excess glucocorticoids, hyperthyroidism, hyperparathyroidism, lung cancer, metastatic cancer, milk-alkalosis syndrome, multiple myeloma, osteoporosis, Paget's disease, renal tubular acidosis, sarcoidosis, vitamin D poisoning, Wilson's disease. Medications: Ammonium chloride, androgens, anabolic steroids, antacids, antiepileptic, cholestyramine, furosemide, parathormone, phosphates, vitamin D.
- Decrease: Hypothyroidism, malabsorption, renal osteodystrophy, vitamin D deficiency. Medications: corticosteroids, aspirin, indomethacin, oral contraceptives, thiazide diuretics.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
