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Myotonic dystrophy is a multisystemic disorder affecting skeletal muscle. Male patients have an increased risk of fractures and develop a number of endocrine/metabolic impairments known to adversely affect bone health. The aim of this study was primarily to determine the occurrence of fragility fractures and the bone mineralization status (lumbar spine, hip and total body by dual X-ray absorptiometry) in 36 male patients affected with type 1 myotonic dystrophy and 13 male patients affected with type 2 myotonic dystrophy. Fragility fractures occurred in 15 type 1 and 7 type 2 myotonic dystrophy in non-classical osteoporotic sites, such as metatarses. Hip osteopenia was the most frequent finding, particularly in type 2 (n = 6) than type 1 myotonic dystrophy patients (n = 1), while osteoporosis was rare. Patients with type 1 myotonic dystrophy presented higher total body bone mass density than patients with type 2 myotonic dystrophy and healthy controls and lumbar spine was associated positively with the severity of the disease. Gonadic failure, with low testosterone and reduced INSL3 levels, visceral adiposity and insulin resistance correlated with reduced body mass index in both type 1 and type 2 myotonic dystrophic patients. The independent determinant of fragility fractures were low total body mass index, low blood testosterone and low global muscle mass., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Hypogonadism occurs in myotonic dystrophies type 1 (MD1) and type 2 (MD2). Sertoli and Leydig cell secretions, including insulin-like peptide-3 (INSL3), anti-Müllerian hormone (AMH) and inhibin B, were evaluated in male patients with MD., Design: Academic settings. Forty-four male patients with MD [31 MD1, 13 MD2, aged 59 (50-64) years, median (interquartile range)], age-, sex- and BMI-matched non-MD hypogonadal patients (n = 14) and healthy controls (n = 32). Serum FSH, LH, inhibin B, AMH, testosterone (T) and INSL3 were measured; fat and muscle masses were evaluated by DEXA., Results: Overt primary hypogonadism occurred in 29% of patients with MD1 and 46% of patients with MD2. Considering subclinical forms, the prevalence increased to 69% of MD1 and 100% of MD2. A half of patients with MD experienced symptoms. INSL3 levels were unaffected in most patients with MD. By contrast, AMH and inhibin B were reduced in most patients with MD and unrelated to age. Patients with MD showed increased body and visceral fat. Free T levels were negatively predicted by fat mass, and AMH and FSH levels were negatively correlated with waist/hip ratio and fat mass. AMH, inhibin B and FSH levels positively correlated with muscle strength and muscle mass., Conclusions: AMH and inhibin B secretion failures are common in male patients with MD and are more severe than Leydig cell hormones impairment. AMH and inhibin B measurements might provide clinical utility in evaluating fertility in patients with MD. Serum T, AMH and inhibin B productions are negatively influenced by increased fat mass, while AMH and inhibin B might be markers of muscle impairment., (© 2015 Stichting European Society for Clinical Investigation Journal Foundation.)

Parathyroid function in Myotonic Dystrophy (DM) patients has been poorly investigated. Parathyroid and muscle parameters were assessed in 31 male DM1 (44±2 years), 13 male DM2 (56±2 years) and 32 healthy controls. Hyperparathyroidism was diagnosed in 18% of patients without differences between DM types. In all DM patients, hyperparathyroidism was associated with normocalcemia but one with hypercalcemia. DM patients presented significantly higher PTH and lower vitamin D (25OHD) compared with controls, also considering seasonality. Severe vitamin D deficiency (25OHD<10 ng/ml) was diagnosed in 40% and hypovitaminosis D (25OHD<30 ng/ml) occurred in 88% of DM patients. About one-third of DM1 presented hypophosphatemia associated with elevated PTH levels. Serum 25OHD levels negatively correlated with PTH and with body fat mass. Considering DM1 patients, serum PTH levels positively correlated with CTG triplet repeats. Furthermore, PTH levels negatively correlated with total modified Medical Research Council (MRC) and positively with Muscular Impairment Rating Scale (MIRS). By contrast, in DM2 patients muscle assessment did not show any correlation with parathyroid function. In conclusion, we arrived at the following: 1) severe vitamin D deficiency is common in DM patients and it is associated with secondary hyperparathyroidism; 2) primary hyperparathyroidism, though rare, may occur; 3) increased adiposity in DM may be a risk factor for hypovitaminosis D; and 4) high serum PTH levels may indicate a muscle impairment, at least in DM1., (Copyright © 2013 Elsevier B.V. All rights reserved.)