Osteoporosis
Dr. Janis R. Guilbeau
University of Louisiana
at Lafayette
College of Nursing and Allied
Health Professions
Essentials of Diagnosis
• Fracture propensity of
spine, hip, pelvis, and wrist
from demineralization.
• Serum PTH, calcium,
phosphorus, and alkaline
phosphatase usually
normal.
• Serum 25-hydroxyvitamin
D levels often low as a
comorbid condition.
Findings
• loss of bone osteoid that reduces bone integrity
• increased risk of fractures
• US causes 2 million fractures annually, including
547,000 vertebral fractures, 300,000 hip fractures, &
135,000 pelvic fractures.
• White women have a 40% lifetime risk of sustaining one
or more osteoporotic fractures.
• Morbidity & mortality rates are very high. The rate of
bone formation is often normal, whereas the rate of bone
resorption is increased.
Signs & Symptoms
• Osteoporosis: usually asymptomatic until fractures occur.
• may present as backache of varying degrees of severity or as
a spontaneous fracture or collapse of a vertebra
• Loss of height is common.
• Once osteoporosis is identified, a carefully directed history and
PE must be performed to determine its cause
Lab Findings
• Serum calcium, phosphate, & PTH are normal.
• alkaline phosphatase is usually normal but may be slightly
elevated, especially following a fracture.
• Vitamin D deficiency is very common & serum determination of
25-hydroxyvitamin D should be obtained for every individual
with low bone density.
• Serum 25-hydroxyvitamin D levels below 20 ng/mL are
considered frank vitamin D deficiency. Lesser degrees of
vitamin D deficiency (serum 25-hydroxyvitamin D levels
between 20 ng/mL and 30 ng/mL) may also increase the risk
for hip fracture.
Bone Densitometry
• DXA: to determine bone density of lumbar spine & hip.
• Bone densitometry: should be performed on all patients at risk
for osteoporosis or osteomalacia or pathologic fractures or
radiographic evidence of diminished bone density. Bone
densitometry cannot distinguish osteoporosis from osteomalacia;
& both are often present. Bone mineral density in typically
expressed in gm/cm2, for which there are different normal ranges
for each bone & for each type of DXA-measuring machine.
• The "T score" is a simplified way of reporting bone density in
which the patient's bone mineral density is compared to the
young normal mean & expressed as a standard deviation score.
T score & Z score
• WHO: criteria for defining osteoporosis in postmenopausal women,
based on T score: T score –1.0: Normal.
• T score –1.0 to –2.5: Osteopenia ("low bone density").
• T score < –2.5: Osteoporosis.
• T score < –2.5 with a fracture: Severe osteoporosis.
• Most women with fragility fractures have bone densities above –2.5.
Surveillance DXA bone densitometry is recommended for
postmenoapausal women with a frequency according to their T scores:
obtain DXA every 5 years for T scores –1.0 to –1.5, every 3–5 years for
scores –1.5 to –2.0, and every 1–2 years for scores under –2.0.
• The "Z score" is used to express bone density in premenopausal
women, younger men, & children. The Z score is a statistical term that
is used for expressing an individual's bone density as standard
deviation from age-matched, race-matched, and sex-matched means.
Differential Diagnoses
• Osteopenia & fractures can be caused by osteomalacia & bone
marrow neoplasia such as myeloma or metastatic bone
disease.
• Conditions may coexist
Prevention & Treatment
• Osteoporosis: Diet: adequate in protein, total calories, calcium, &
vitamin D. Pharmacologic corticosteroid doses should be reduced or
discontinued if possible.
• Thiazides may be useful if hypercalciuria is present.
• High-impact physical activity significantly increases bone density; Stairclimbing
• Exercise regularly, increasing strength & reducing the risk of falling.
• Weight training is helpful to increase muscle strength as well as bone
density. Measures should be taken to avoid falls at home. Patients who
have weakness or balance problems must use a cane or a walker;
rolling walkers should have a brake mechanism. Balance exercises can
reduce the risk of falls. Bedridden patients should be given active or
passive exercises.
• Alcohol & smoking should be avoided.
Treatment
• Treatment is indicated for all women with osteoporosis
(T scores below –2.5) and for all patients who have had
fragility fractures.
• Prophylactic treatment should also be considered for
patients with advanced osteopenia (T scores between –
2.0 and –2.5).
Vitamin D & calcium
•
Osteoporosis & osteomalacia often coexist
•
Sun exposure & vitamin D supplementation are useful in preventing & treating
osteomalacia.
•
Vitamin D supplementation reduces the incidence of vertebral fractures.
•
Oral vitamin D is given in doses of 800–2000 international units daily.
•
Vitamin D supplementation is especially required during winter months & for patients
having prolonged hospitalization or nursing home care, for patients with serum levels of
25-hydroxyvitamin D below 20 ng/mL, & those with intestinal malabsorption.
•
Calcium supplementation does not reduce the fracture risk in otherwise healthy
postmenopausal women.
•
Calcium supplementation is indicated principally for those with diets low in calcium. More
important is the assurance of adequate vitamin D through sun exposure or oral vitamin D
supplementation, & calcium supplementation should include vitamin D.
•
Calcium supplementation: calcium citrate (0.4–0.7 g elemental calcium per day) or calcium
carbonate (1–1.5 g elemental calcium per day).
Bisphosphonates
• inhibiting osteoclast-induced bone resorption. They increase
bone density significantly and reduce the incidence of both
vertebral and nonvertebral fractures. Bisphosphonates have
also been effective in preventing corticosteroid-induced
osteoporosis. To ensure intestinal absorption, oral
bisphosphonates must be taken in the morning with at least 8
oz of plain water at least 40 minutes before consumption of
anything else.
Sex Hormones
• Hypogonadal women who take estrogen replacement therapy
(ERT) have a lower risk of developing osteoporosis.
• Postmenopausal estrogen replacement is valuable as an
osteoporosis prevention measure & this should be one factor in
the complex decision about whether to take ERT.
• Low doses of estrogen: prevent postmenopausal osteoporosis
Selective estrogen receptor
modulators
• can be used by postmenopausal women in place of estrogen
for prevention of osteoporosis.
• Raloxifene produces a reduction in LDL cholesterol but not the
rise in high-density lipoprotein (HDL) cholesterol seen with
estrogen
• Teriparatide stimulates the production of new collagenous bone
matrix that must be mineralized.
Calcitonin
• A nasal spray of calcitonin-salmon (Miacalcin) is available that
contains 2200 units/mL in 2-mL metered-dose bottles.
• usual dose is one puff (0.09 mL, 200 international units) once
daily, alternating nostrils. Calcitonin reduces the incidence of
vertebral fractures, but its effect upon nonvertebral fractures
has not been established.
Denosumab
• Monoclonal antibody that inhibits the proliferation & maturation
of preosteoclasts into mature osteoclast bone-resorbing cells.
• Denosumab is administered in doses of 60 mg subcutaneously
every 6 months.
• It is extremely expensive.
Prognosis
• Bone mineral density densitometries can detect whether
progressive osteopenia or frank osteoporosis is developing.
• Hypogonadal women, especially those not receiving HRT, must
ensure sufficient intake of vitamin D to prevent osteomalacia.
• Bisphosphonates & raloxifene can reverse progressive
osteopenia & osteoporosis & decrease fracture risk.