Running low on calcium isn't always obvious. You might notice muscle cramps, tingling around the mouth or fingertips, brittle nails, or more broken bones than you'd expect. Severe low calcium can cause spasms or even seizures, so it's not something to ignore.
Who tends to be low on calcium? Older adults, people who avoid dairy, strict vegans, and anyone with vitamin D deficiency or digestive issues that reduce absorption. Certain medicines — like long-term steroids, some anticonvulsants, and proton pump inhibitors — can lower calcium over time. Chronic kidney disease also messes with calcium balance.
Your doctor will usually start with a blood test for total serum calcium and may correct that value for albumin. They may also check ionized calcium, parathyroid hormone (PTH), and vitamin D. If low calcium is suspected long-term, a DEXA scan (bone density) can show whether bones are losing mineral. If you’re on meds that affect calcium or have repeated fractures, get tested sooner rather than later.
Food first. Dairy (milk, yogurt, cheese) is the easiest source. Non-dairy options that absorb well include canned salmon with bones, sardines, fortified plant milks, tofu set with calcium, and low-oxalate leafy greens like kale and bok choy. Spinach is high in calcium but also high in oxalates, which block absorption.
Supplements when needed. Two common forms are calcium carbonate and calcium citrate. Carbonate has more elemental calcium (around 40%) and works best with meals. Citrate is easier on an empty stomach and for people with low stomach acid. Aim to take no more than 500–600 mg of elemental calcium per dose — your body absorbs smaller amounts better — and split larger daily needs into two doses.
Daily targets: many adults need about 1,000 mg daily; women over 50 and men over 70 often target about 1,200 mg. Pair calcium with adequate vitamin D — D helps your gut absorb calcium. Weight-bearing exercise also helps keep calcium in your bones.
Watch for interactions and risks. Calcium can reduce absorption of iron, thyroid meds, and some antibiotics, so space doses by a couple of hours. High supplemental calcium may raise the risk of kidney stones in some people; discuss risks with your clinician.
If you have frequent muscle cramps, unexplained fractures, numbness, or a lab showing low calcium, see your doctor. They can find the cause — whether it’s diet, a medicine, low vitamin D, or a medical condition — and set a safe plan to restore balance.
At SpringMeds, we cover practical guides on supplements, tests, and safe shopping for meds and vitamins. If you’re unsure where to start, a quick blood test and a chat with your provider will point you in the right direction.
