Urine calcium can be estimated using a laboratory test. Three main hormones are responsible for the metabolism of calcium in the body: calcitonin, parathyroid hormone and calcitriol. Excessive excretion of calcium in the urine is called calcariuria.
Normal urinary calcium values are at least 4 mg per kilogram of weight (per 24 hours), that is, on average from 100 to 250 mg / 24 hours (women) and from 100 to 300 mg / 24 hours (men). The reference values may vary slightly from laboratory to laboratory, and also due to the calcium content in the diet. A low calcium diet is 150 mg / 24 hours or less. Diet average calcium intake of 100-250 mg / 24 hours. High dietary calcium intake of 250-300 mg / 24 hours.
It must be remembered that approximately 98-99% of calcium is filtered in the glomeruli of the kidneys (10 g per day), 60% is reabsorbed. Parathyroid hormone and activated vitamin D contribute to the absorption of calcium from blood plasma. Calcitonin also contributes to the absorption of calcium, increasing the amount of mineral in the bones and lowering the level of calcium in the serum.
Urine collection should begin in the morning. All urine excreted in 24 hours should be collected in an appropriate container. Between urination, the container is stored in the refrigerator.
Urine collection ends after 24 hours with complete urination. In women of childbearing age, urine collection should not be carried out during menstruation due to the risk of contamination of the sample and incorrect interpretation of the analysis.
Causes of hyper Calcariuria:
- hyperparathyroidism: an increase in the functionality of the parathyroid glands, usually due to benign tumors;
- kidney failure;
- excessive intake of vitamin D or calcium-rich foods;
- idiopathic hypercalciuria;
- hyperthyroidism and thyrotoxicosis: excess thyroid hormones;
- the use of certain medications: diuretics (furosemide), antacids (calcium carbonate).
Other causes of increased excretion of calcium in the urine include bone fractures, prolonged immobilization, the use of high protein and sodium diets, tumors with bone metastases (typical cases of breast and lung cancer , tumors that release substances like parathyroid hormone (paraneoplastic syndrome), Paget's disease.
An indicator of the level excreted in urine calcium is an important diagnostic sign, ignoring of which can lead to serious consequences.