The gold standard for assessing bone mineral density (BMD) & diagnosis of osteoporosis is:
A i.e. Dual energy X Ray absorptiometry Dual Energy X-ray Absorptiometry (DEXA) is the gold standard and investigation of choice for diagnosis of osteoporosis and assessing bone mineral density (BMD)Q. DXA/DEXA/Dual Energy X-ray Absorptiometry It is a highly accurate X-ray technique that has become the standard for measuring bone density in most centers. Standard X-rays cannot detect bone loss until 30% of bone has been lost; where as DXA can detect as little as 1% of bone loss. However DXA is a two dimensional scanning technique and cannot estimate the depths or posteroanterior length of the bone. Thus small people tend to have lower then average bone minerals density (BMD). Bone spurs, which are frequent in osteoporosis, tend to falsely increase bone density of the FDA approved indications for BMD tests are: Estrogen deficient women at risk of osteoporosis Gliicocoicoid treatment equivalent to 7.5 mg of prednisole, or duration of therapy > 3 months Primary hyper parathyroidismQ Veebral abnormalities on X-ray suggestive of osteoporosis (osteopenia, veebral fracture) Monitoring response to an FDA-approved medication for osteoporosis Repeat BMD evaluation at > 23 month intervals, or more frequently if medically justified. Biochemical markers of bone metabolism in clinical use are spine. - Though it can be used for measurement of any skeletal site, clinical determinations are usually made of the lumbar spine and hip. Poable DXA machines have been developed that measures the heel (Calcaneus), forearm (radius & ulna) and finger (phalanges) - In DXA, two scores are used 1) T - score: is more impoant and compares individual results with to those in young population (of same race & gender) t-score Interpretation Upto -1 S.D. Normal -1 to -2.5 S.D. Osteopenia < - 2.5 S.D. Osteoporosis S.D. = Standard detion 2) Z - Score: Compares individual with same age population (same race & gender) . Bone Formation Bone Resorption - Serum bone specific Urine & serum cross linked N ? alkaline telopeptide phosphataseQ Urine & serum cross linked C ? - Serum osteocalcinQ telopeptide Urine total free - Serum peptide of deoxypyridinoline type I procollagenQ Urine hydroxyproline Urine hydroxylysine glycosides Serum tarate - resistant acid phosphatase Serum bone sialoprotein * Noninvasive techniques for measurement of Bone mass in osteoporosis Dual Energy X Ray Absorptiometry (DEXA)Q = Gold standard & investigation of choice Single Energy X Ray absorptiometry (SEXA) USG CT Scan - provides a true density but expensive & has greater radiation exposure.
Dual energy X-ray absorptiometry
Single energy X-ray absorptiometry
Ultrasound
Quantitative computed tomography