Laboratory findings:
The concentrations of calcium and inorganic phosphorus in the blood are usually
normal. Slight hyperphosphatemia occurs in women who are past the menopause.
The alkaline phosphatase in uncomplicated
instances is normal but may increase after fractures. About 20% of postmenopausal
women with osteoporosis have hypercalciuria.
Urinary excretion of peptides
containing hydroxyproline, “an index of bone” resorption, is usually
normal or slightly increase in those with high-turnover osteoporosis.
Serum levels of oesteocalcin (bone GLA protein), urinary excretion of hydroxypyidinium
cross-link compounds, and uptake of Tc-methylene disphoshonate also correlate
with the rate of bone turnover.
Treatments
In
considering treatment, it should be emphasized that one is dealing with a group
of disorders rather than a single entity. Even in patients within the same category,
e.g. those with idiopathic osteoporosis, the ethiologies may be different.
It is also difficult to predict the course; especially in patients seen because
of pain and collapse-fracture. Many patients in the idiopathic, postmenopausal
(type1), and senile (type 2) groups have a few episodes of vertebral body collapse
but then go for many years without symptoms or further loss in height.
Furthermore, the acute pain associated with vertebral body fracture tends to subside
in weeks, and any treatments administered at that time might be considered efficacious.
Although accurate estimation of bone mass can help determine efficacy
of therapy, clinical benefit (diminution of bone pain, decrease in incidence of
fractures) is more difficult to assess in view of variability in disease progression.
It is generally agreed, however, that estrogen replacement in women is effective
in preventing bone loss after oophorectomy or early in the menopause.
General
measures
Patients
with acute pain secondary to fracture of vertebral bodies frequently require rest
in bed in a position of maximum comfort, local heat, adequate analgesics, and
avoidance of constipation.
Use of traction or plaster jackets splints
is not indicated. As soon as pain permits, the patient should attempt to move
out of bed, slowly at first, perhaps with support of a walker or cruches.
Braces are commonly employed, but their efficacy in preventing progression
of spinal deformity is not established. A well-made corset may provide support
and comfort.
Exercises to correct postural deformity and increase muscle tone are useful. Patients
should be taught to avoid sudden painful movements such as jumping and how to
lift and carry objects with minimal back strain.
After the fractures
have healed, a supervised exercise program that includes daily walking may be
helpful in preventing further skeletal losses.
Calcium
supplements
Women
who are estrogen-deprived require an average oral intake of 1500 mg/d of elemental
calcium to remain in calcium equilibrium. The recommendation of the National Institute
of Health of 1000 mg elemental calcium per day for women on estrogen replacement
and for men is reasonable.
In postmenopausal women unable to take estrogens,
the use of 1500 mg/d of oral calcium may have minor benefit in preserving cortical
bone but has no effects on trabecular bone mass.
Adequate calcium intake
before age 30 to 35 may enhance peak bone mass, however. The content of elemental
calcium of available preparations.
Vitamin D preparations have been
used in osteoporosis because calcium absorption is impaired and levels of the
active metabolite, 1, 25(OH)2D , are marginally low in serum.
Subclinical
vitamin D deficiency and associated secondary hyperparathyroidism are common in
elderly women, particular those confined to nursing homes.
In these
women, low doses of vitamin D (800 IU daily) combined with calcium supplements
are effective in maintaining bone mass and decreasing incidence of hip fractures.
Oral
administration of calcitriol [1, 25(OH)2D] also may improve intestinal calcium
absorption suppress bone reabsorption, and prevent bone loss in postmenopausal
osteoporosis.
Bone formation is not increase, however, and the dose used in one study caused
hypercalcemia and hypercalciuria. Thiazide diuretics are useful in patients with
high turnover osteoporosis associated with hypercalciuria and secondary hyperparathyroidism.
In the absence of secondary hyperparathyroidism, the Thiazide diuretics
lower urinary calcium excretion, suppress parathyroid gland function, inhibit
synthesis of 1, 25(OH)2D, and reduce intestinal calcium absorption.
Calcitonin
Calcitonin
decrease bone resorption, and the use of salmon Calcitonin in established osteoporosis
has been recommended in doses of 50 units subcutaneously every other day.
Patients with high-turnover osteoporosis (elevated levels of serum osteocalcia,
increased urinary hydroxyproline excretion, and increased total –body retention
of Tc-methylene disphosphonate) appears to respond best with improvement in bone
mass.
Another approach involves the use of salmon Calcitonin administered
by nasal spary (200 unit per day) to avoid injections.
Bisphosphonates
The Bisphosphonate etidronate has been used cyclically, alternating with calcium
and vitamin D, to inhibit bone resorption without producing osteomalacia.
In the studies reported, the effects of etidronate on bone mass were similar
to those of estrogen and Calcitonin. It is not yet certain, however, whether therapy
with etidronate prevents fractures. Bisphosphonates that do not inhibit mineralization
of bone may prove to be more useful antiresorptive agents.
Fluoride
Fluoride
ions are deposited in the skeleton, where they become incorporated into the crystal
lattice of hydroxyyapatite, substituting for hydroxyl ions.
This process
results in a mineral phase of greater crystallinity. Sodium fluoride or intermittent
low doses of PTH (currently in therapeutic trails) are the only agents that can
stimulate osteoblastic proliferation and function and increase bone formation.
Indeed, chronic ingestion of high amounts of fluoride, usually in endemic
areas where fluoride contents of drinking water is high, produces a from of hyperostosis,
with dense bones, exostoses, neurologic complications due to bony overgrowth,
and ligament ossification.
Increased amounts of bone with excessive osteoid
is evidence of stimulation of bone formation. When sodium fluoride is used to
treat osteoporosis, there is a continuous increase in bone mass of the spine.
Insome series this increase in bone mass is accompanied by decrease incidence
of spinal fractures, but the therapy may results in an increased risk of fractures
of hip as well as other nonvertebral fractures.
Even in series in which a satisfactory effect of sodium fluoride is observed,
some patients do not respond at all. Some patients do develop side effects including
knee, foot, and ankle pain attributed to microfractures; other patients cannot
tolerate with fewer gastrointestinal and rheumatologic complications.
In any case, calcium supplements with or without vitamin D are necessary to prevent
bone mineralization defects that accompany the use of sodium fluoride alone. Lower
doses of sodium fluoride may be effective in lowering fracture risk in subjects
with osteoporosis without loss of bone quality.
