This study demonstrates that unopposed oestrogen replacement therapy during 2 months in postmenopausal women slightly, but significantly, increases total serum leptin levels. This observation suggests a role for oestrogens in the regulation of leptin.

Calcium uptake from the gut is increased by GH effects on vitamin D metabolism or action. Bone metabolism is stimulated by many factors, of which GH and insulin-like growth factor I (IGF-I) are only two examples. From various animal and human data, it can be shown that GH and IGF-I seem to influence bone formation more than bone resorption. However, GH excess, as seen in acromegaly, does not result in increased bone mass. GH was used to treat osteoporosis in a few clinical trials. In only one, in combination with calcitonin, an increase in bone mass was observed. In GH-defïcient adult patients, substitution therapy resulted in a temporary increase in serum calcium levels. Effects on bone mineral mass were only found in a pilot study performed by us in a group of 8 GH-deficient adult patients. The mean increase of bone mineral mass was 0.04 g hydroxypatite/cm², p < 0.05. These data indicate that GH substitution can result in increased bone mass.

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder leading to progressive heterotopic ossifications (HO) of muscles, tendons, and ligaments, which can be induced by trauma or by surgery. Despite strong medical advice to the contrary, an FOP patient insisted on surgery to alleviate her complete trismus, which caused an unbearable impact on her quality of life (QOL). The entire trismus history of this FOP patient is presented. [18F]‐NaF position emission tomography/computed tomography (PET/CT) scans were introduced as an imaging method for heterotopic bone formation activity. To place our findings into context, a systematic review on jaw surgery in FOP was performed. After falling down the stairs, a 9‐year‐old patient developed mobility impairment of her left‐sided jaw. During the following 13 years bone scintigraphy showed persistent activity of the disease leading to progressive left‐sided zygomatico‐mandibular fusion by HO, resulting in complete trismus. Within 1 month after HO removal on the left side and a matching right coronoidectomy, [18F]‐NaF PET/CT demonstrated a substantial flare‐up activity followed by new HO in both masseter and temporalis muscles. Despite recurrent HO and trismus her QOL increased due to a stable increased interincisal opening of 5.5 mm. Although systematic review reveals a 100% risk of HO recurrence after jaw surgery, information on improved QOL is scarce. In conclusion, surgery in FOP may be beneficial for QOL despite new HO formation. Assessment of disease activity using [18F]‐NaF PET/CT is possible before HO is evident on CT and may serve as a new and quantitative marker of the disease. © 2017 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Circulating concentrations of 1,25-dihydroxyvitamin D, 24,25-dihydroxyvitamin D and 25-hydroxyvitamin D were measured in 21 anephric subjects. 13 subjects had no therapy with vitamin D, dihydrotachysterol or lα-hydroxyvitamin D₃. In 7 subjects of this group 1,25-dihydroxyvitamin D was undetectable ( < 5 pmol/l). In the other 6 patients concentrations ranged from 10 to 43 pmol/l (reference value 111 ± 33 pmol/l). All subjects taking high doses of vitamin D showed detectable 1,25-dihydroxyvitamin D concentrations in the same range. Dihydrotachysterol therapy caused spuriously high ‘1,25-dihydroxyvitamin D’ values, probably by interference of a metabolite of dihydrotachysterol in our assay. In subjects on vitamin D or dihydrotachysterol therapy 25-hydroxyvitamin D concentrations were significantly elevated (314 ± 146 nmol/l and 98 ± 19 nmol/l, respectively; reference value 52 ± 22 nmol/l). Concentrations of 24,25-dihydroxyvitamin D were only measured in subjects without vitamin D₂ intake. In general very low but detectable concentrations were found. One subject on a high dose of vitamin D₃ showed a 24,25-dihydroxyvitamin D₃ concentration of 10.2 nmol/l (reference value 4.4 ± 2.9 nmol/l). Our results therefore confirm earlier reports on extrarenal synthesis of 24,25-dihydroxyvitamin D and suggest that there may be extrarenal production of 1,25-dihydroxyvitamin D as well.

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