Natasha M. Appelman-Dijkstra

Pituitary Dysfunction in Adult Patients after Cranial Radiotherapy: Systematic Review and Meta-Analysis

CONTEXT Cranial radiotherapy is an important cause of hypopituitarism. The prevalence of hypopituitarism varies considerably between studies. OBJECTIVE We conducted a systematic review and meta-analysis of reported prevalences of hypopituitarism in adults radiated for nonpituitary tumors. DATA SOURCES We searched PubMed, EMBASE, Web of Science, and the Cochrane Library to identify potentially relevant studies. STUDY SELECTION Studies were eligible for inclusion with the following criteria: 1) cranial radiotherapy for nonpituitary tumors and/or total body irradiation for hematological malignancies; 2) adult population (>18 yr old); and 3) report on endocrine evaluation. DATA EXTRACTION Data review was done by two independent reviewers. Besides extraction of baseline and treatment characteristics, also endocrine tests, definitions, and cutoff values used to define pituitary insufficiency were extracted. RESULTS Eighteen studies with a total of 813 patients were included. These included 608 patients treated for nasopharyngeal cancer (75%) and 205 for intracerebral tumors. The total radiation dose ranged from 14 to 83 and 40 to 97 Gy for nasopharyngeal and intracerebral tumors, respectively. The point prevalence of any degree of hypopituitarism was 0.66 [95% confidence interval (CI), 0.55-0.76]. The prevalence of GH deficiency was 0.45 (95% CI, 0.33-0.57); of LH and FSH, 0.3 (95% CI, 0.23-0.37); of TSH, 0.25 (95% CI, 0.16-0.37); and of ACTH, 0.22 (95% CI, 0.15-0.3), respectively. The prevalence of hyperprolactinemia was 0.34 (95% CI, 0.15-0.6). There were no differences between the effects of radiotherapy for nasopharyngeal vs. for intracerebral tumors. CONCLUSION Hypopituitarism is prevalent in adult patients after cranial radiotherapy for nonpituitary tumors. Therefore, all patients treated by cranial radiotherapy should have structured periodical assessment of pituitary functions.

Bone Material Strength as Measured by Microindentation In Vivo Is Decreased in Patients With Fragility Fractures Independently of Bone Mineral Density

CONTEXT Bone mineral density (BMD) does not fully capture fracture risk as the majority of fractures occur in patients with osteopenia, suggesting that altered bone material properties and changes in microarchitecture may contribute to fracture risk. OBJECTIVE This study aimed to evaluate the relationship between bone material strength (BMS), measured by microindentation in vivo, and fracture in patients with low bone mass. METHODS BMS was measured in 90 patients (mean age, 61.0 y; range, 40.4-85.5 y) with low bone mass with or without a fragility fracture. Sixty-three patients had sustained one or more fragility fractures. RESULTS There was a significant negative correlation between age and BMS (r = -0.539; P < .001) and with the 10-year fracture probability with and without inclusion of femoral neck BMD as calculated by FRAX (r = -0.383; P < .001 and r = -0.426; P < .001, respectively). BMS values were lower in patients with a fragility fracture compared with nonfracture patients (79.9 ± 0.6 vs 82.4 ± 1.0; P = .032) despite similar BMD. BMS was comparable in patients with a fragility fracture whether they had osteopenia or osteoporosis (79.8 ± 0.8 vs 78.7 ± 1.1; P = .456). In patients with osteopenia, BMS was significantly lower in fracture patients than in nonfracture patients (80.3 ± 0.7 vs 83.9 ± 1.2; P = .015). CONCLUSION These data suggest that patients with fractures have altered material properties of bone that are not captured by BMD. Additional studies are required to establish the value of BMS in the prediction of fracture risk, especially in patients with osteopenia.

The IGSF1 Deficiency Syndrome: Characteristics of Male and Female Patients

CONTEXT Ig superfamily member 1 (IGSF1) deficiency was recently discovered as a novel X-linked cause of central hypothyroidism (CeH) and macro-orchidism. However, clinical and biochemical data regarding growth, puberty, and metabolic outcome, as well as features of female carriers, are scarce. OBJECTIVE Our objective was to investigate clinical and biochemical characteristics associated with IGSF1 deficiency in both sexes. METHODS All patients (n = 42, 24 males) from 10 families examined in the university clinics of Leiden, Amsterdam, Cambridge, and Milan were included in this case series. Detailed clinical data were collected with an identical protocol, and biochemical measurements were performed in a central laboratory. RESULTS Male patients (age 0-87 years, 17 index cases and 7 from family studies) showed CeH (100%), hypoprolactinemia (n = 16, 67%), and transient partial GH deficiency (n = 3, 13%). Pubertal testosterone production was delayed, as were the growth spurt and pubic hair development. However, testicular growth started at a normal age and attained macro-orchid size in all evaluable adults. Body mass index, percent fat, and waist circumference tended to be elevated. The metabolic syndrome was present in 4 of 5 patients over 55 years of age. Heterozygous female carriers (age 32-80 years) showed CeH in 6 of 18 cases (33%), hypoprolactinemia in 2 (11%), and GH deficiency in none. As in men, body mass index, percent fat, and waist circumference were relatively high, and the metabolic syndrome was present in 3 cases. CONCLUSION In male patients, the X-linked IGSF1 deficiency syndrome is characterized by CeH, hypoprolactinemia, delayed puberty, macro-orchidism, and increased body weight. A subset of female carriers also exhibits CeH.

Progression of Vertebral Fractures Despite Long-Term Biochemical Control of Acromegaly: A Prospective Follow-up Study

BACKGROUND In active acromegaly, pathologically elevated GH and IGF-1 levels are associated with increased bone turnover and a high bone mass, the latter being sustained after normalization of GH values. In a cross-sectional study design, we have previously reported a high prevalence of vertebral fractures (VFs) of about 60% in patients with controlled acromegaly, despite normal mean bone mineral density (BMD) values. Whether these fractures occur during the active acromegaly phase or after remission is achieved is not known. OBJECTIVE Our objective was to study the natural progression of VFs and contributing risk factors in patients with controlled acromegaly over a 2.5-year follow-up period. METHODS Forty-nine patients (mean age 61.3 ± 11.1 years, 37% female) with controlled acromegaly for ≥ 2 years after surgery, irradiation, and/or medical therapy and not using bisphosphonates were included in the study. Conventional spine radiographs including vertebrae Th4-L4 were assessed for VFs according to the Genant method. VF progression was defined as development of new/incident fractures and/or a minimum 1-point increase in the Genant scoring of preexisting VFs. BMD was assessed by dual-energy x-ray absorptiometry (Hologic 4500). RESULTS Prevalence of baseline VFs was 63%, being highest in men, and fractures were unrelated to baseline BMD. VF progression was documented in 20% of patients, especially in men and in case of ≥ 2 VFs at baseline. VF progression was not related to BMD values or BMD changes over time. CONCLUSION Findings from this longitudinal study show that VFs progress in the long term in 20% of patients with biochemically controlled acromegaly in the absence of osteoporosis or osteopenia. These data suggest that an abnormal bone quality persists in these patients after remission, possibly related to pretreatment long-term exposure to high circulating levels of GH.

The role of vitamin D in human fracture healing: a systematic review of the literature

INTRODUCTION Vitamin D is essential for bone mineralization and for the subsequent maintenance of bone quality. Mineralization is part of hard callus formation and bone remodelling, processes, which are part of fracture healing. We provide a comprehensive review of the literature to summarize and clarify if possible, the cellular effects of vitamin D and its clinical involvement in the process of fracture healing in human. MATERIAL AND METHODS We conducted a literature search in PubMed, Embase (OVID version), and Web of Science. RESULTS A total of 75 in vitro and 30 in vivo studies were found with inconsistent results about the cellular effect of vitamin D on fracture involved inflammatory cells, cytokines, growth factors, osteoblasts, osteoclasts and on the process of mineralization. With only five in vitro studies performed on material derived from a fracture site and one in vivo study in fracture patients, the exact cellular role remains unclear. Seven studies investigated the circulating vitamin D metabolites in fracture healing. Although it appears that 25(OH)D and 24,25(OH)2D3 are not affected by the occurrence of a fracture, this might not be the case with serum concentrations of 1,25(OH)2D3. The potential clinical effect of vitamin D deficiency is only described in one case series and three case controlled studies, where the results tend to show no effect of a vitamin D deficiency. No clinical studies were found investigating solely vitamin D supplementation. Two clinical studies found a positive effect of vitamin D supplementation and calcium, of increased bone mineral density or respectively increased fracture callus area at the fracture site. One study found indirect evidence that vitamin D and calcium promoted fracture healing. CONCLUSION Despite these results, and the presumed beneficial effect of vitamin D supplementation in deficient patients, clinical studies that address the effects of vitamin D deficiency or supplementation on fracture healing are scarce and remain inconclusive. We conclude that vitamin D has a role in fracture healing, but the available data are too inconsistent to elucidate how and in what manner.

Long-term effects of recombinant human GH replacement in adults with GH deficiency: a systematic review

BACKGROUND The beneficial effects of recombinant human GH (rhGH) therapy in GH deficient (GHD) adults are well-established in the short term. However, data documenting the effects during prolonged follow-up are relatively scarce. OBJECTIVE To evaluate the reported effects of rhGH replacement (≥5 years) in GHD adults on biochemical and anthropometric parameters, quality of life (QoL), bone metabolism, muscle strength, serious adverse events and mortality. METHODS We conducted a systematic literature search. Quality assessment of retrieved papers was performed using a quality assessment based on the modified STROBE statement. RESULTS We included 23 prospective studies with a rhGH treatment duration ranging from 5 to 15 years. Overall, beneficial effects were reported on QoL, body composition, lipid profile, carotid intima media thickness and bone mineral density. In contrast, the prevalence of the metabolic syndrome, glucose levels, BMI and muscle strength were not, or negatively, influenced. Most of the studies were uncontrolled, lacked the presence of a control group (of non-treated GHD patients), and reported no data on lipid-lowering and anti-diabetic medication. Overall mortality was not increased. CONCLUSION rhGH treatment in adult GHD patients is well-tolerated and positively affects QoL in the long term. However, the metabolic and cardiovascular effects during long-term treatment are variable. The low numbers of long-term studies and studied patients and lack of control data hamper definite statements on the efficacy of prolonged treatment. Therefore continuous monitoring of the effects of rhGH replacement to enable an adequate risk-benefit analysis that may justify prolonged, potentially life-long, treatment is advisable.

Metabolic Profile in Growth Hormone-Deficient (GHD) Adults after Long-Term Recombinant Human Growth Hormone (rhGH) Therapy

BACKGROUND The metabolic effects of recombinant human GH (rhGH) therapy in adults are well-documented in the short term. The effects of long-term rhGH therapy beyond 5 yr on metabolic parameters are presently unknown. OBJECTIVE The aim of the study was to evaluate the long-term effects of rhGH treatment on biochemical and anthropometric parameters in a large cohort of GH-deficient adults. METHODS Ninety-eight GH-deficient adult patients treated with rhGH for at least 10 yr were included (mean age, 59.4 yr; 50% female). Total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, anthropometric parameters, IGF-I, and glucose were evaluated at baseline and after 5, 10, and 15 yr of treatment. In addition, the prevalence of the metabolic syndrome (MS) and the incidence of cardiovascular events were assessed. RESULTS Total cholesterol and low-density lipoprotein cholesterol concentrations were lower, and high-density lipoprotein cholesterol levels were significantly higher during long-term rhGH replacement when compared to baseline (all P < 0.001). Both waist circumference (P < 0.001) and body mass index (P = 0.018) were significantly higher after 10 yr, as were fasting plasma glucose levels (P < 0.001). No significant changes were observed in triglycerides, waist-to-hip ratio, and blood pressure during follow-up. In the subset of patients with 15-yr rhGH treatment (n = 43), generally similar metabolic effects were found. MS prevalence was increased after 10 yr of rhGH treatment (57.1 vs. 32.7%; P < 0.001), especially in males (69.4 vs. 32.7%; P < 0.001). CONCLUSION Despite improvement of several cardiovascular risk factors, MS prevalence increased significantly during rhGH treatment. The effect of long-term rhGH treatment on overall cardiovascular risk profile needs to be established in a larger cohort.

Novel approaches to the treatment of osteoporosis

Despite the availability of efficacious treatments for fracture reduction in patients with osteoporosis, there are still unmet needs requiring a broader range of therapeutics. In particular, agents that are capable of replacing already lost bone and that also drastically reduce the risk of non-vertebral fractures are needed. Studies of rare bone diseases in humans and animal genetics have identified targets in bone cells for the development of therapies for osteoporosis with novel mechanisms of action. Here, we review these new developments, with emphasis on inhibitors of cathepsin K in osteoclasts and sclerostin in osteocytes, which are currently studied in phase 3 clinical trials.

Sclerostin Inhibition in the Management of Osteoporosis.

The recognition of the importance of the Wnt-signaling pathway in bone metabolism and studies of patients with rare skeletal disorders characterized by high bone mass identified sclerostin as target for the development of new therapeutics for osteoporosis. Findings in animals and humans with sclerostin deficiency as well as results of preclinical and early clinical studies with sclerostin inhibitors demonstrated a new treatment paradigm with a bone building agent for the management of patients with osteoporosis, the antifracture efficacy, and long-term tolerability of which remain to be established in on-going phase III clinical studies. In this article we review the currently available preclinical and clinical evidence supporting the use of sclerostin inhibitors in osteoporosis.

Modulating Bone Resorption and Bone Formation in Opposite Directions in the Treatment of Postmenopausal Osteoporosis

Bone remodeling, the fundamental process for bone renewal, is targeted by treatments of osteoporosis to correct the imbalance between bone resorption and bone formation and reduce the risk of fractures and associated clinical consequences. Currently available therapeutics affect bone resorption and bone formation in the same direction and either decrease (inhibitors of bone resorption) or increase (parathyroid hormone [PTH] peptides) bone remodeling. Studies of patients with rare bone diseases and genetically modified animal models demonstrated that bone resorption and bone formation may not necessarily be coupled, leading to identification of molecular targets in bone cells for the development of novel agents for the treatment of osteoporosis. Application of such agents to the treatment of women with low bone mass confirmed that bone resorption and bone formation can be modulated in different directions and so far two new classes of therapeutics for osteoporosis have been defined with distinct mechanisms of action. Such treatments, if combined with a favorable safety profile, will offer new therapeutic options and will improve the management of patients with osteoporosis.