Calcium is the primary mineral constituent of our bones and one of the most important minerals in our bodies. Our cells, nerves, heart, muscles, bones, teeth, and blood clotting all require calcium. With more and more people receiving diagnosis of osteopenia and osteoporosis it’s a topic I wanted to explore a little more. 

But what determines how much calcium is in your body?

• Is it to do with much you’re getting from food?
• Is it to do with how much you’re absorbing in your intestines?
• Is it related to phosphate levels in the body?
• Can hormone levels (including parathyroid, estrogen, calcitonin) affect it?

When blood calcium levels are too low, the body takes it from bones to release calcium and bring the blood level back to normal.

When blood calcium levels get too high, that surplus has to go somewhere… so it goes to the bones, soft tissues, stool, or the urine.

However, doctors don’t routinely test it by itself unless there is an obvious need, but oftentimes it is part of a Comprehensive metabolic panel. A blood calcium test is usually more accurate in detecting certain conditions like specific bone diseases, pancreatitis, and hyperparathyroidism.

What’s A Normal Blood Calcium Level For A Healthy Adult?

In reference to blood calcium levels, Dr. Jim Norman of the Norman Parathyroid Center says:

“We have several hundred ‘normal’ calcium levels in our database—no adult human has calcium levels below 9.0 mg/dL (this is in the US measurement of milligrams per deciliter (mg/dL), and 99% are between 9.3 and 9.9. 90% are between 9.5 and 9.8.” He has also shared that it’s “typically not normal for adults to have frequent or persistent (blood) calcium levels in the 10s.” 

When serum calcium is frequently in the 10s, medical doctors would consider investigating hyperparathyroidism and even certain types of cancer.

Why Would I Want A Urine Calcium Test?

If you’re excreting high amounts of calcium, it could be an indicator of bone loss. To determine if this is really happening a 24-Hour Urine Calcium Test can help detect this.

This 24-Hour Urine Calcium Test will help identify if you’re peeing out too much calcium (also called hypercalciuria). The standard reference range that’s considered normal is 100 – 300 mg/24 hrs.

If you’re taking in 1,200mg calcium a day, most would agree that your urine calcium levels should be less than 300mg. Ideally, you want to be on the lower to middle end of this range. 100, 150, even 200… That’s considered about average for most adults even without osteoporosis.

If your levels are greater than 300 mg in 24 hours (>300 mg/24 hr) it could be an indicator of one of the following: 

• Hyperparathyroidism: Parathyroid glands overproducing parathyroid hormone (can also cause fatigue, back pain, and sore bones)
• Sarcoidosis: An inflammatory disease that affects the lymph nodes, lungs, liver, eyes, skin, or other tissues
• Too much calcium in your diet/supplement plan (Milk-alkali syndrome)
• Excessively high Vitamin D levels
• Drug-induced calcium loss with loop diuretics
• Chronic kidney disease / kidney failure
• Hyperthyroidism (overactive thyroid)
• Renal tubular acidosis: When the kidneys don’t function properly they can’t remove excess acid in the blood.
• Malignancy or Myeloma
• Even a testing error

As I mentioned previously, high urine calcium results can also be an indicator of bone loss (osteoporosis and osteopenia). If your levels are elevated, it may be worth repeating along with a more extensive workup.

What Could A Low Urine Calcium Result Indicate?

24-Hour Urine calcium levels lower than the 100 – 250mg in a 24-hour period could indicate…

• Nutrient malabsorption
• Poor kidney function
• Hypoparathyroidism (Lack of parathyroid hormone production)
• Low Vitamin D levels

Both the blood calcium test and urine calcium test need to be an important part of your lab testing plan and discussion with your doctor.

There’s a lot more to a proper workup than that but this is a good start. When it comes to testing you need to be your own best advocate, do your research so you know what to ask for and how to do so confidently (it’s your health on the line here). The first step is to understand what the results mean so you can take the appropriate action.

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