Pocket ObGyn – Osteoporosis
See Abbreviations
Definition (Obstet Gynecol 2012;120:718)
- Low bone mass, microarchitectural deterioration, increased bone Defined by WHO based on DEXA T-scores:
T-score: Std deviation from mean BMD of a healthy young (30 yo) adult
Nml: T-score ³–1
Osteopenia: T-score <–1 but >–2.5
Osteoporosis: T-score <–2.5
Z-score: Std deviation from mean BMD of age-matched pop, informative in cases of sev osteoporosis
Epidemiology (AJOG 2006;194:S3)
- 8–17% US postmenopausal women have osteoporosis
- Incid increases w/ age ® 48–70% affected by age 80
- By age 70, Caucasian women in US have a 40% risk of hip, spine, or forearm fracture
Etiology
| Osteoporosis risk factors | |
| Etiologies | Risk factors |
| Age-dependent bone loss | Age |
| Low bone mass | Thin, small frame Caucasian, Asian
Prev personal fracture FHx of fracture |
| Estrogen deficiency (hypogonadal states) | Postmenopausal Amenorrhea Anorexia nervosa |
| Etiologies | Risk factors |
| Endocrine disorders | Hyperparathyroidism Hyperthyroidism DM |
| GI disorders | Celiac dz & malabsorption Pancreatic dz
Gastric bypass or GI Surg |
| Nutrition | Calcium,Vit D, protein deficiency |
| Meds | Depo-Provera Glucocorticosteroids
Gonadotropin-releasing hormone agonists Heparin & anticonvulsants Tamoxifen, cancer chemotherapeutics |
| Lifestyle | Cigarette smoking, excessive EtOH use Sedentary |
Clinical Manifestations
- Clinically silent until Hip fracture, esp trochanteric vs. intracapsular, is the most serious complication.Vertebral fracture often p/w back pain, kyphosis, & loss of ht. Forearm fracture also possible.
Screening
- FRAX risk assessment tool (www.shef.ac.uk/FRAX/) calculates 10-y fracture
- DEXA (gold std) at 65 yo, earlier if postmenopausal w/ fracture, or risk factors (h/o fragility fracture, body wt <127 lb, medical causes of accelerated bone loss, smoker, alcoholism, rheumatoid arthritis, FHx of hip fracture in parent). FRAX 10-y risk >3% (65 yo risk) ® early screening. Rpt screening not earlier than 2 y unless new risk factor.
| DEXA screening guidelines | |
| Organization | Criteria |
| National Osteoporosis Foundation | All women over age 65
Personal h/o bone fracture after 50 <65 & postmenopausal w/ risk factors |
| USPSTF | All women over age 65
All women whose FRAX fracture risk is >9.3% due to risk factors |
| ACOG | All women over age 65 |
| <65 w/ more than 1 risk factor or FRAX 9.3% risk of fracture | |
- Other screening modalities (US, CT, x-ray, photon absorptiometry) are available but are less cost-effective, accurate, &
- Biochemical markers of bone turnover include:
Bone resorption markers: Hydroxyproline, pyridinium cross-links
Bone formation markers: Alk phos, osteocalcin, procollagen I propeptides Fasting urinary calcium/Cr ratio indicates balance btw resorption & formation
Treatment and Medications
- Prevention and nonpharmacologic: Regular weight-bearing exercise + 800 IU Vit D daily + 1200 mg calcium daily + avoid cigarette smoking & excessive EtOH Fall precautions for older or unsteady pts. ACOG calcium/Vit D recommendations: Age 9–18: Calcium 1300 U QD,Vit D 600 U QD
Age 19–50: Calcium 1000 U QD,Vit D 600 U QD
Age 51–70: Calcium 1200 U QD,Vit D 600 U QD
Age ≥70: Calcium 1200 U QD,Vit D 800 U QD
- Pharmacologic: Initiate rx for >50 yo & vertebral/hip fracture or T-score £–2.5 at the femoral neck or spine or T-score –1 to –2.5 at the femoral neck or spine & 10-y fracture risk ³3% or 10-y osteoporosis fracture risk ³20% or low trauma fracture (esp vertebral/hip).
Bisphosphonates: 1st line, oral or IV administration (alendronate, risedronate, ibandronate, etidronate). Side effects – esophagitis, myalgias
SERM: Oral (raloxifene). Side effects – vasomotor sx, DVT, leg cramps Calcitonin: Subcutaneous or nasal administration. Side effects – nausea, rhinitis Parathyroid hormone: Subcutaneous administration. Side effects – HyperCa,
nausea, leg cramps
Estrogen: Oral, transdermal administration. WHI demonstrated ¯ osteoporosis for both estrogen alone & estrogen–progestin therapy. Side effects – VTE, cardiovas(ccu)lar2d0z1, b5reWastoclatnecresr. Kluwer. All Rights Reserved.
- Monitoring resp to therapy: F/u DEXA 2 y after beginning of therapy, decreased frequency thereafter if adequate resp. N-telopeptide urine measurement is useful in monitoring drug compliance or in pts w/ malabsorption, only useful if on antiresorptive meds.