J Korean Soc Endocrinol.  1998 Mar;13(1):60-66.

Clinical Applicability of Ultrasonometric Skin Thickness Measurement in the Diagnosis of Postmenopausal Osteoporosis: Comparison with DXA

• Kim YS
• Han IK
• Lee DJ
• Kim KM

Abstract

BACKGROUND: Osteoporosis is developed by progressive decrease of bone rnass from decreased collagen content of bone. Accurate measurement of bone collagen is necessary for the diagnosis of osteoporosis and it is possible by bone biopsy, however bone biopsy is not easy in clinical practice. Skin collagen is consist with type I collagen which is same type of bone collagen and progressive decrease of bone collagen is reflected by decrease of skin collagen. Since skin thickness reflect skin collagen amount, skin thickness measurement may be a useful method for the evaluation of osteoporosis. So ultrasonic skin thickness measurement was developed for the evaluation of osteoporosis.
METHODS
A randomly selected 200 women aged fram 30 to 71 years old were asked to have their skin thickness measured as well as lumbar vertebral DXA(Norland, USA) bone densitometry. Except for the two women who failed to complete the study, 45(22.7%) of these women were diagnosed as normal, 74(37.4%) were osteopenic and 79(39.9%) were diagnosed as osteoporosis patients using the WHO criteria. Skin thickness was measured using 20MHz Osteoson DCIII (Minhorst, Germany) at the medial side of the upper arm. A minimal of Two scans were measured and the mean value was cakulated automatically.
RESULTS
The correlation coefficient of skin thickness and age was -0.121(ns), DXA BMD(bone mineral density) and age was -0.420(P<0.01), skin thickness and DXA BMD L2-L4 was 0.181(P<0.05). Skin thickness was significantly correlated with body weight(correlation coefficient 0.254, P<0.01) and BMI(correlation coefficient 0.195, P<0.01). Furthermore, the mean and standard deviation of skin thickness in normal BMD group was 0.94+-0.021mm, osteopenic group was 0.92+-0.006mm, and osteoporotic group was 0.89+-0.018mm. There was statistically significant difference in the mean values of skin thickness between the three groups even adjusted with age and BMI(P<0.05). The mean and standard deviation of skin tbickness of healthy 20-40 year old women was 1.11+-0,023mm and their mean and standard deviation of L2-L4 mean BMD was 1.17+-0.145mg/cm2. The diagnostic predictability of skin thickness less than 1mm as the risk of osteoporosis(BMD T score less than -1.0) was evaluated. The sensitivity and the specificity of skin thickness less than 1mm being osteoporotic were 78,2% and 57.8% respectively. The positive and negative predictive value of the skin thickness less than 1mm being osteoporotic were 82.2% and 36.5% respectively.
CONCLUSION
This study indicate that the skin thickaess measured with the ultrasound method show good correlatian with the bone density measured with conventional DXA at the lumbar vertebra and the skin thickness less than 1mm on the medial side of the opper arm is relatively sensitive in diagnosing osteoporosis risk in Korean women. The authors suggested that a large randomized control study to define the relationship between the skin thickness and the other determinants of bone turnover in the near future.

MeSH Terms

Aged
Arm
Biopsy
Bone Density
Collagen
Collagen Type I
Densitometry
Diagnosis*
Female
Humans
Osteoporosis
Osteoporosis, Postmenopausal*
Sensitivity and Specificity
Skin*
Spine
Ultrasonics
Ultrasonography
Collagen
Collagen Type I