Calcium is perhaps the most essential nutrient when it comes to bone health.
Building strong bones is like building a healthy balance in your “calcium bank account.”
Bones are living tissue and constantly in a state of turnover, making calcium deposits and withdrawals daily.
Bones don't come with a lifetime guarantee. They need continuous maintenance or they can weaken and break.
If your diet is low in calcium, your body will take calcium from your bones to keep blood calcium at normal levels.

Decide on the best treatment for the most common type of kidney stone, which is made of calcium.
This type of stone may occur when the kidney leaks too much calcium into the urine.
Monitor someone who has a problem with the parathyroid gland, which helps control calcium levels in the blood and urine.
Help diagnose the cause of problems with your blood calcium level or bones.

High levels of urine calcium may be due to:

Chronic kidney disease
High vitamin D levels
Leaking of calcium from the kidneys into the urine, which causes calcium kidney stones
Sarcoidosis
Taking too much calcium
Too much production of parathyroid hormone (PTH) by the parathyroid glands in the neck (hyperparathyroidism)
Use of loop diuretics

Low levels of urine calcium may be due to:

Disorders in which the body does not absorb nutrients from food well
Disorders in which the kidney handles calcium abnormally
Parathyroid glands in the neck do not produce enough PTH (hypoparathyroidism)
Use of a thiazide diuretic
Very low levels of vitamin D