Gynecology: Osteoporosis

Guest · **posting in usmle forum about Obstetrics & Gynecology**

1. Overview:
=============
1. Bone mass peaks at age 30 and gradually declines thereafter. Bone loss accelerates after menopause to 1.5% per year, then slows again after 10-15 years.

2. Osteoporosis is decreased bone mass with normal ratio of mineral to matrix. A bone mineral density (BMD) T score below 2.5 standard deviations below the mean for young adults is considered osteoporosis.

3. Osteopenia is decreased bone mass with a T score between 1 and 2.5 standard deviations below the mean for young adults.

4. Risk factors for osteoporosis include exercise-related amenorrhea, time since menopause, corticosteroid use, thin body habitus, sedentary lifestyle, inadequate calcium or Vitamin D intake, family history of osteoporotic fractures, white or Asian race, high alcohol consumption, smoking, hyperthyroidism, chronic kidney or liver disease, and long-term therapy with corticosteroids, thyroid hormone, anticonvulsants, or heparin.

5. Protective factors include obesity, diabetes mellitus, thiazide diuretic use, and possibly statins.

6. Fractures resulting from osteoporosis include hip fractures (with 5%-20% mortality rate within 3 months), vertebral compression fractures (causing loss of height, kyphosis, and resulting pulmonary, GI, and bladder problems), Colles’ fracture and tooth loss.

2. Diagnosis:
=============
1. Radiographs will show osteopenia only after there is 20% to 30% bone loss.

2. DEXA scan is the most accurate method of measuring bone mineral density (BMD) but is not recommended as a routine screening test. Measuring BMD is useful when it will make a significant difference in management as in the decision of whether to start hormone replacement therapy.

3. Osteoporotic fractures are often the first indication of osteoporosis.

4. Differential diagnosis. Once osteoporosis is diagnosed, consider whether there is an underlying condition that might be causing osteoporosis: hyperparathyroidism, chronic renal failure, multiple myeloma, leukemia, lymphoma, hyperthyroidism, excessive thyroid replacement, hypercortisolism, metastatic cancer.

3. Prevention:
==============
1. Calcium intake: Adolescents and reproductive-age women producing endogenous estrogen require 1000 mg of calcium daily through diet or supplements. Postmenopausal women require 1500 mg daily if not taking estrogen or raloxifene. Calcium should be taken with meals in doses up to 500 mg. Calcium carbonate is cheapest, although calcium citrate is better absorbed.

2. Vitamin D intake of 400 IU (perhaps 800 IU after age 70) through fortified milk, multivitamin or supplement is required for absorption of calcium. Deficiency is especially common in winter in the higher latitudes, and in institutionalized patients.

3. Exercise. Regular weight-bearing exercise such as running, weight training, aerobics, walking and sports excluding swimming.

4. Quit smoking and avoid excessive alcohol use.

5. Minimize corticosteroid and thyroid hormone use as much as possible. If on chronic steroids, vitamin D and calcium ± alendronate (or risedro-nate) should be considered.

6. Alendronate 5 mg PO QD or 35mg PO once a week is used for pre- vention of osteoporosis in postmenopausal women as is risedronate 5 mg/day.

7. Modify the home environment to identify and eliminate factors predisposing to falls.

4. Treatment:
=============
All of the following therapies should be accompanied by adequate calcium and Vitamin D intake.

1. Hormone replacement therapy with estrogen or raloxifene especially in women with premature or surgical menopause.

2. Bisphosphonates are effective monotherapy, and have a small additive effect when given with hormone replacement therapy. They are also useful in corticosteroid-related osteoporosis.

1. Alendronate (10 mg PO once a day or 70 mg PO once a week, which is just as effective) has been shown to reduce the risk of vertebral fractures by 90% and nonvertebral fractures by 30%-50% in established osteoporosis. To prevent esophageal ulceration, it must be taken in the morning with 8 oz water at least 1/2 hour before any other foods or fluids are taken and the patient must remain upright until after the first meal.

2. Etidronate is an alternative. It is given cyclically, 400 mg PO QD for 2 weeks, followed by 12 weeks without the drug. It is probably as effective as alendronate.

3. Risedronate is the most potent bisphosphonate and also has the lowest incidence of GI side effects. It is approved for osteoporosis in a dose of 5.0 mg/day for both prevention and treatment.

4. Salmon calcitonin--1 spray in alternating nostrils each day is expensive but effective in increasing BMD. It relives the pain of vertebral compression fractures.

5. Thiazides especially in patients needing an antihypertensive, increase bone mass and have an additive effect with estrogen.

6. Fluoride, although it increases bone density, actually increases hip fracture risk, so it is no longer used.