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How healthy are your bones?

Understanding the results of diagnostic testing

Susan Brown, PhDby Dr. Susan Brown, PhD

Unless you’re a medical professional, you may not be familiar with the tests that we recommend for finding out what is causing your osteoporosis. While your physician will tell you exactly what your test results mean in your particular case, it might be helpful for you to understand some generalities about what these test results can mean so that the information you get from your physician can be put into context.

Vitamin D 25(OH)D blood test results

The test used to assess vitamin D adequacy is the 25(OH)D blood test. The reported “normal” range is very wide, often from 30 to 100 ng/mL. We now know that anything less than 32 ng/mL is likely to seriously limit calcium absorption and lead to bone loss. At the Center for Better Bones, we strive for a 50-70 ng/mL blood level of 25(OH)D.

Ionized calcium test results

The body controls free calcium in the blood very tightly, with a normal laboratory range between 4.8 and 5.2 mg/dL (between 1.2 and 1.3 mmol/L) as reported by the Merck Index. While there are many medical uses and interpretations of the ionized calcium blood test, when thinking of bone health, we look for high ionized calcium as a possible indirect indicator of excessive parathyroid hormone activity. Also, from a nutritional point of view, a low ionized calcium level might be related to low albumin and low protein status.

Intact parathyroid hormone blood test (iPTH) results

At the Center for Better Bones, we look for an intact parathyroid hormone level within the normal range established by the particular testing laboratory. Two common causes of an excessively high parathyroid hormone level are: (1) vitamin D deficiency (which is easily corrected with proper vitamin D3 supplementation and monitoring); and (2) an overactive parathyroid, which is most often due to benign tumors on the parathyroid glands. Correction of this situation often requires surgery to remove the overactive glands.

Excessively high parathyroid hormone levels cause the body to release too much calcium from the bone. This contributes to bone loss, but perhaps more importantly, it results in high blood calcium, which can be a serious matter in its own right. A high parathyroid condition is best treated by an endocrinologist.

24-hour urine calcium excretion test results

Blood constantly flows through the kidneys and is “cleansed” and filtered. In this fashion, each day the kidneys filter several thousands of milligrams of calcium, most of which are recycled back into the blood. A small amount of this calcium, however, is lost in the urine. This 24-hour urine collection measures the amount of calcium lost in the urine. The normal laboratory range for a person eating an average diet is around 100 to 250 mg of calcium lost in the urine each day. At the Center for Better Bones, we consider a calcium loss of more than 250 mg to be a concern. In such cases, the first step is to stop all calcium supplements for 4 to 5 days and then retest the 24-hour urine calcium. If the urine calcium loss is still high, then steps should be taken to reduce this loss of calcium in the urine, as it can enhance bone loss. Nutritional, lifestyle, and medical approaches are available for reducing calcium loss in the urine.

Thyroid hormone function test (TSH) results

The thyroid gland produces hormones that regulate metabolism. It produces two hormones, called T3 and T4. When too much of these hormones are in the body, it leads to bone loss. This situation can occur for two reasons: first, because the thyroid gland is overactive and producing too much of these hormones (a condition called hyperthyroidism), and second, because the thyroid gland is under-producing hormones, and the replacement hormones that have been prescribed to address this problem are at too high a dose. Underactive thyroid (or hypothyroidism) is far more common than hyperthyroidism, particularly in women in their middle years.

TSH is a hormone produced in the pituitary gland that signals the thyroid to produce more of its hormones. If TSH is high, it usually means that the thyroid isn’t producing enough T3 and T4, so checking your TSH level is a simple way of screening for an underactive thyroid. The common laboratory range for all adults is 0.35 to 5.50 and a more ideal level is 0.35 to 2.0. To screen for overactive thyroid, or to make sure your dose of thyroid medications isn't too high if you're already being treated for hypothyroidism, you'll need tests for free T3 and free T4.

N-telopeptides crosslinks (NTx) urine marker of bone resorption test results

The test result “normal” range often listed on the test report is very broad. For example, test reports from our local lab list the premenopausal normal range for women as 17-94 nM BCE/mM creatinine and the postmenopausal range as 26-124 nM BCE/mM creatinine. The male range is 3-51. These ranges are far too wide to be useful.

Ideally, a woman would like to have an NTx level near that of the average premenopausal woman, which in the urine is around 35, but levels often soar into the 60’s to 80’s or higher in and around menopause. For adult men, the mean NTx is 27, which is a more ideal value than the higher numbers. Also, these markers can get very high in rare diseases such as Paget’s Disease and bone cancer. These situations are unusual and understood by a knowledgeable physician familiar with bone resorption testing.

At the Center for Better Bones, we use the NTx urine test from Osteomark to judge the success of our bone building program. We look to bring the urine NTx level down to the 40’s, which in most cases indicates that bone breakdown has normalized. There are some cases, however, where bone breakdown is very low, but bone build-up is even lower. This condition, known as “low turnover osteoporosis,” is detected when a person has a low NTx, but is still losing significant bone (5-6%) as seen on bone density testing.

N-telopeptides crosslinks (NTx) serum marker of bone resorption test results

The NTx bone-breakdown marker can also be measured in the blood. The female range listed by the manufacturer is 6.2-19.0 nM BCE/L, with a mean of 12.6. The male range is often listed as 5.4-24.2 nM BCE/L, with a mean of 14.8. Again, this range is too wide to be useful for us at the Center for Better Bones. We strive for a result of 12 or somewhat lower in women, and 14 or somewhat lower in men.

Dpd urine marker of bone resorption test (deoxypyridinium crosslinks test) results

This bone resorption test also lists a broad range of normal values — for women, 3.0 to 7.4 nM/mM and for men 2.3 to 5.4 nM/mM. Clinically, adult women should strive for a Dpd test score in the 4’s, and in men an ideal level would likely be somewhat lower.

Vertebral deformity assessment results

This test images the vertebral bodies of the spine by x-ray technique and is read by a specially trained radiologist. The radiologist will give a full report of what he or she sees for each vertebral body, reporting any abnormalities, deformities, or fractures.

Free cortisol test (blood or saliva) results

Cortisol is the “get up and go” hormone that should rise in the early morning and decline during the day. Thus, test results vary by what time of day the test was taken. Testing labs will give their normal range readings and the timing of the test should be taken into account when interpreting test results. This test can be done with blood or saliva.

DHEA test (blood or saliva) results

This test also can be done with blood or saliva. In saliva testing, the results are often correlated with the results of the cortisol testing. It is also often measured as DHEA-S, that is, DHEA in its sulfated form. Again, each lab will offer its normal range depending on the test used.

C-reactive protein test (high sensitivity if possible) results

Generally, in the C-reactive protein (or CRP) test, the lower the score the less inflammation and thus the better reading. We at the Center for Better Bones strive for a high sensitivity CRP level less than 1.0mg/dL.

Homocysteine test (plasma or serum) results

Normal levels of homocysteine in the blood range from 5 to 15 mM/L. At the Center for Better Bones we like to see a homocysteine level of 8 or below.

Celiac disease and gluten sensitivity test results

There are varied tests used to help determine if one is suffering from the autoimmune disease known as celiac disease, or if there exists the intolerance of gluten sensitivity. For an updated review of these tests and their usefulness see, The Whole-Body Approach to Osteoporosis by R. Keith McCormick, New Harbinger Publications, 2008.

Sex hormone test results

Post-Menopausal Females: Progesterone, Estrogen
Both blood and saliva testing are available for sex hormones. Each testing laboratory will have its range of normal sex hormone test results.

Pre-Menopausal Females (reproductive years hormone testing): Progesterone, Estrogen
Both blood and saliva testing are available for pre-menopause sex hormone testing. Each testing laboratory will have its range of normal sex hormone test results.

Sex Hormone Testing in Males: Testosterone and, at times, Estrogen
Both blood and saliva testing are available for sex hormone tests in men. Each testing laboratory will have its range of normal sex hormone test results.

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Original Publication Date: 01/20/2010
Last Modified: 06/04/2014
Principal Author: Dr. Susan E. Brown, PhD