A friend recently mentioned that she was dealing with a calcium problem postpartum. This caught me off guard. In my iron-obsessed world, calcium deficiency isn’t something I hear about often outside of my mom’s aging concerns.

But as I started digging into the research, the patterns looked familiar.

Just like with iron, you can have “normal” blood calcium levels even when you’re actually deficient. Your labs come back normal, your doctor says you’re good, and meanwhile, your bones are working overtime.

So what’s really happening here? If blood tests are our standard first line of screening, how are we supposed to catch this early? And who’s most at risk of slipping through the cracks?

Your body keeps blood calcium levels stay stable at all costs, drawing on bone stores and adjusting how much your kidneys and gut absorb and excrete.

A serum calcium test tells you what’s in your blood right now. And it’s held normal by bone resorption and hormonal regulation until very late-stage deficiency. It completely misses early bone loss.

Bone density or imaging shows your long-term skeletal stores, but it’s more expensive and isn’t routine for screening for younger women. They’re usually ordered only after problems are suspected.

There is actually no single, accurate test to definitively diagnose calcium deficiency. In practice, doctors typically rely on how much of it you’re eating and life stage to judge whether you’re getting enough.

When dietary intake is low, hormones like parathyroid hormone (PTH) and vitamin D increase calcium release from bone into the blood. And this compensation works remarkably well.

The result is that women can stay in the early and middle stages of deficiency for years with normal blood calcium and declining bone health. By the time blood calcium actually drops, you’ll already have significant bone loss.

Women have higher calcium turnover through menstruation, pregnancy, lactation, and menopause. And the most recent findings report more than 27% of high-income countries have intakes below 800 to 1000 mg per day¹.

Low calcium intake during pregnancy has been linked to greater bone loss and lower maternal bone density up to 5 years after delivery.

Though fairly rare, pregnancy-associated osteoporosis is a real thing. If we screened your prenatal yoga class of maybe 20 women, it’s likely that 1 or 2 women would be in osteoporotic range in terms of bone density!

If relying on blood calcium means waiting for late-stage deficiency, when the damage is already done, we need to pay attention to different signals.

The most relevant question becomes whether your daily intake consistently meets your needs right now. Calcium requirements increase during adolescence, pregnancy, breastfeeding, high-impact or endurance training, irregular cycles, perimenopause, and menopause.

Calcium also doesn’t work in isolation. It needs enough vitamin D, adequate overall energy intake, and basic hormonal health to maintain your bones. Under-eating, chronic stress, and low estrogen undermines your body’s ability to maintain your bones, even when consuming enough calcium.

Finally, symptoms and history matter. Recurrent stress fractures, bone pain, or dental issues are meaningful signals worth paying attention to, even if your blood tests look fine.

If you want a practical takeaway on calcium and early detection, here it is:

🥛 Do a calcium intake check.
Estimate your intake for a typical day. You should aim for about 1,000 mg.

☀️ Anchor calcium to vitamin D.
If you supplement or intentionally increase calcium intake, pair it with adequate vitamin D exposure or supplementation, so that it can actually be used by bone.

🦴 Adjust intake during high-demand phases.
Increase your focus on calcium during pregnancy, breastfeeding, heavy training, irregular cycles, and the menopausal transition.

🗣️ Use history to guide monitoring.
Past stress fractures, long-term low intake, eating restriction, or RED-S are valid reasons to discuss earlier bone density assessment, regardless of your age.

📅 Treat bone health as cumulative.
Small daily gaps can add up quickly, so think about your intake as consistency over years.