Urinary calcium is

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

in the

urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excreted from the body through the urethra. Cellular ...

. It is termed -calcuria or -calciuria as a suffix.

Normal amount

In a

urinalysis Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic ...

, the normal amount of urinary calcium can be measured in amount per time (commonly per 24 hours). It can also be measured in amount per mass of

creatinine Creatinine (; ) is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body (depending on muscle mass). Biological relevance Serum creatinine (a blood measurement) is an importa ...

, which avails for estimating the urinary calcium excretion in a spot urine sample, because urinary

creatinine clearance Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging. Functions of a healthy kidney include maintaining a person's fluid ...

is relatively unaffected by differences in free water clearance which occurs, for example, in

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

and which would distort the interpretation of the urinary calcium in a spot urine sample. Normally, in an average adult, the amount of calcium excreted in the urine is 100–250 mg over a 24-hour period.medscape.com > Urine Calcium: Laboratory Measurement and Clinical Utility
By Kevin F. Foley, PhD, DABCC; Lorenzo Boccuzzi, DO. Posted: 12/26/2010; Laboratory Medicine. 2010;41(11):683-686. © 2010 American Society for Clinical Pathology. In turn citing: *Wu HBA. Tietz Guide to Clinical Laboratory Tests. 4th ed. St. Louis, MO: Saunders, Elsevier; 2006. For those on low-calcium diets, there is normally 50–150 mg/24 hours, while those on a calcium-free diet will have 5–40 mg/24 hours. The following

reference range In medicine and health-related fields, a reference range or reference interval is the range or the interval of values that is deemed normal for a physiological measurement in healthy persons (for example, the amount of creatinine in the blood, o ...

s are for persons with average calcium intake (600–800 mg/day for adults):

Disorders

An abnormally high amount of urinary calcium is called

hypercalciuria Hypercalciuria is the condition of elevated calcium in the urine. Chronic hypercalciuria may lead to impairment of renal function, nephrocalcinosis, and chronic kidney disease. Patients with hypercalciuria have kidneys that put out higher levels ...

and an abnormally low amount is called hypocalcuria.

References

{{reflist Urine tests