Is a low skinfold thickness an indicator of osteoporosis?

OBJECTIVE: The association between thin skin and osteoporosis has been known for some years. We wished to assess a simple measure of skinfold thickness (SFT) as a screening test for osteoporosis and to study the effect of chronological and menopausal age on SFT in a group of osteoporotic women and normal controls. DESIGN: A case control study of 225 consecutive women who attended an osteoporosis clinic. PATIENTS: We studied 225 women, 141 with osteoporosis (mean age 61.8 +/- 10.5 years) and 65 normal controls (mean age 59.9 +/- 8.8 years), with 19 exclusions. METHODS: Each patient had routine biochemistry, spinal X-rays and a dual-energy X-ray absorptiometry (DEXA) scan of lumbar spine and femoral neck. In addition they had skinfold thickness measured by a single observer using Holtain Tanner Whitehouse callipers over the 4th metacarpal of the right hand. RESULTS: Mean skinfold thickness was lower in the osteoporotic group, 1.6 +/- 0.4 mm compared to normals 1.8 +/- 0.3 mm (P < 0.0001). SFT did not decline significantly with chronological or menopausal age in the normals (correlation coefficients r = -0.06, r = -0.09) in contrast to the osteoporotic group (correlation coefficients r = -0.52, P < 0.001; r = -0.27, P < 0.0001). Subjects with a SFT of < or = 1.5 mm had a higher probability of osteoporosis (odds ratio 3.12, 95% confidence interval 1.58-6.14). Subjects with a SFT of > or = 2.1 mm had a lower probability of osteoporosis (odds ratio 0.305, 95% confidence interval 0.126-0.740). CONCLUSION: Our results demonstrate a lower mean SFT in osteoporotic compared with normal women, with a negative correlation between SFT and chronological and menopausal age in osteoporotics, but not in normal controls. A low skinfold thickness appears to be an indicator of developing osteoporosis and a high SFT may indicate a normal bone mass.