Calcium does far more than build bones — it is essential for nerves, muscles and the heart. Your body keeps blood calcium within a narrow range, so a result outside it is worth understanding.
High calcium (hypercalcemia)
The two most common causes are an overactive parathyroid gland and, less often, certain cancers. Symptoms can include excessive thirst, frequent urination, constipation and fatigue. Your doctor may add a parathyroid hormone (PTH) test to find the cause.
Low calcium (hypocalcemia)
Low levels can result from vitamin D deficiency, kidney disease, low magnesium or parathyroid problems. Severe drops can cause tingling and muscle cramps.
A note on albumin
About half of blood calcium travels bound to albumin, so a low albumin can make calcium look low when the active (ionized) calcium is actually fine. This is why labs sometimes report a corrected calcium.
You don't have to interpret a single number alone. Upload your full lab report and Lab Lens will explain every value in plain English, or browse all our lab test guides.
This article is for general education only and is not medical advice. Reference ranges vary between laboratories — always read your result against the range on your own report and discuss it with your doctor.