Underweight and malnutrition are important risk factors for the development of osteoporosis. Especially in adolescents, they cause significant harm by reducing the maximum bone mass achieved. As highlighted by Dr. Hofmeister, increasing evidence from studies has become available over the last years showing that obesity, too, has a negative impact on bone quality.
In fact, it would be good to find out whether an increase in fat mass, especially morbid obesity, is associated with an increased risk of ankle fractures, lower leg fractures or proximal humeral fractures.
We will gladly take up this suggestion for future data analyses. In the current study, this was not possible as the number of cases was too low. In earlier studies, we have already evaluated the relationship between body mass index, waist circumference, visceral and subcutaneous fat mass, and the stiffness index, as well as vitamin D serum levels (1, 2). These analyses revealed positive linear associations between anthropometric measures and the stiffness index (1). No reduction in stiffness index was detected with increasing body mass index and fat mass, respectively. In contrast, an inverse association between these anthropometric measures and vitamin D levels was found (2).
We would also like to thank PD Dr. Birkenmaier for his comment. As mentioned in the discussion section, the results of our quantitative ultrasound (QUS) measurements of the calcaneus, including the stiffness index and the risk of osteoporotic fracture, are not identical with the clinical diagnosis of osteoporosis (3).
In clinical practice, dual-energy X-ray absorptiometry (DXA) is the accepted gold standard, whereas QUS measurements are recommended only in exceptional cases for the initial diagnosis (4).
Footnotes
Conflict of interest statement
Dr. Wallaschofski has received lecture fees for lectures on “biomarkers of bone metabolism” from Amgen und Lilly.
Dr. Hannemann declares that no conflict of interest exists.
References
- 1.Berg RM, Wallaschofski H, Nauck M, et al. Positive association between adipose tissue and bone stiffness. Calcif Tissue Int. 2015;97:40–49. doi: 10.1007/s00223-015-0008-3. [DOI] [PubMed] [Google Scholar]
- 2.Hannemann A, Thuesen BH, Friedrich N, et al. Adiposity measures and vitamin D concentrations in Northeast Germany and Denmark. Nutr Metab (Lond) 2015;12 doi: 10.1186/s12986-015-0019-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Schürer C, Wallaschofski H, Nauck M, Völzke H, Schober HC, Hannemann A. Fracture risk and risk factors for osteoporosis—results from two representative population-based studies in North East Germany (Study of Health in Pomerania: SHIP-2 und SHIP-Trend) Dtsch Arztebl Int. 2015;112:365–371. doi: 10.3238/arztebl.2015.0365. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Dachverband Osteologie e.V. Prophylaxe. Diagnostik und Therapie der Osteoporose bei Männern ab dem 60. Lebensjahr und bei postmenopausalen Frauen. S3-Leitlinie des Dachverbands der Deutschsprachigen Wissenschaftlichen Osteologischen Gesellschaften e.V. Kurzfassung und Langfassung. www.dv-osteologie.org/dvo_leitlinien/osteoporose-leitlinie-2014. (last accessed on 15 September 2015)