How healthy are your bones?
Understanding the results of diagnostic testing
by 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
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
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
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,
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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Dr. Susan E. Brown, PhD
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Original Publication Date: 01/20/2010
Principal Author: Dr. Susan E. Brown, PhD