Question | Answer |
Osteo risk factors | Hx of fx as adult; Hx of fx in 1st degree relative; current SMK/EtOH; wt <127 lb. Low Ca/vit D |
BMD values | T score: BMD >-1SD below YN = normal.
Severe osteoporosis = <-2.5 |
best predictor of fx risk | bone density (75-85% of variance in bone strength) |
DEXA used for: | PA spine, lateral spine, hip, forearm, total body |
Quantitative CT used for: | spine (trabecular only) |
T-score: osteopenia | -1 to -2.5 SD below YN (young normal) |
Skeletal response to continuously delivered PTH | inc osteoclasts, inc resorption, inc serum Ca |
Skeletal response to once-daily delivered PTH | inc osteoblasts, inc bone formation, inc bone mass/ strength |
Causes of secondary osteoporosis | Hypogonadism, Cushing, thyrotoxicosis, hyperPTH, immobilization, malignancy, multi myeloma, DM, liver dz, celiac, heparin, antiseizure Rx |
Primary postmenopausal osteo: bone loss is | mostly trabecular (very sensitive to estrogen loss) -> vertebral compression fx & distal wrist fx |
Primary senile osteo: characterized by | trabecular and cortical bone loss -> hip fx |
Osteo mgmt | Ca citrate (0.7gm) or Ca CO3 (1-1.5gm elemental Ca). Vit D 800-2000IU/QD. Bisphosphonates. Teriparatide. Monitor BMD & height. |
Difference between osteoporosis and osteomalacia | Osteoporosis: proportional bone mineral and matrix decrease. Osteomalacia: bone mineral decrease only |
Osteomalacia patho | Decreased deposition of Ca & PO4 in bone matrix -> increased epiphysis width & cortical thinning. |
Osteomalacia in kids = | rickets (before closing of epiphyseal growth plates) |
Sx/sx of osteomalacia in kids | Delayed fontanelle closure, growth, & dentition. Rachitic rosary (enlarged costal cartilages), bow legs. |
Sx/sx of osteomalacia in adults | Proximal muscle weakness. Hip pain & antalgic gait. Tetany, muscle wasting, hypotonia (2/2 low Ca). Fractures w/o trauma. |
Osteomalacia tx | Vit D (50,000-100,000 U/week) and Ca. Monitor urinary Ca. Calcitriol if renal failure. |
Renal osteodystrophy (osteitis fibrosa or osteomalacia) MOA | CKD: kidneys fail to eliminate PO4 and poorly synthesize calcitriol -> compensatory increase in PTH |
Paget disease patho | Hereditary (AD) vs viral. Rapid formation & resorption of bone -> replaced by dense trabecular bone w/abnormal architecture w/areas of weakening -> fx and may compress nerves (CN VIII) |
Dietary requirement of Ca: | 1000-1500 mg/day |