The role of vitamin D in the pathogenesis and treatment of diabetes mellitus: a narrative review.

Diabetes mellitus, a metabolic disorder associated with chronic complications, is traditionally classified into two main subtypes. Type 1 diabetes mellitus (T1DM) results from gradual pancreatic islet ß cell autoimmune destruction, extending over months or years. Type 2 diabetes mellitus (T2DM) is a heterogeneous disorder, with both insulin resistance and impairment in insulin secretion contributing to its pathogenesis. Vitamin D is a fat-soluble vitamin with an established role in calcium metabolism. Recently, several studies have provided evidence suggesting a role for it in various non-skeletal metabolic conditions, including both types of diabetes mellitus. Preclinical studies of vitamin D action on insulin secretion, insulin action, inflammatory processes, and immune regulation, along with evidence of an increase of hypovitaminosis D worldwide, have prompted several epidemiological, observational, and supplementation clinical studies investigating a potential biological interaction between hypovitaminosis D and diabetes. This narrative review aims to summarize current knowledge on the effect of vitamin D on T1DM and T2DM pathogenesis, prevention, and treatment, as well as on micro- and macrovascular complications of the disease. Furthermore, on the basis of current existing evidence, we aim to highlight areas for potential future research.

Pathogenesis of propylthiouracil-related hepatotoxicity in children: present concepts.

Propylthiouracil (PTU), carbimazole (CMZ) and methimazole (MMI) are the most common drugs used today in cases of adolescent thyrotoxicosis. Skepticism has been growing regarding the use of PTU in childhood and its association with severe liver failure. The aim of this review is to present all the recent data regarding pathogenesis of PTU hepatotoxicity in children and adolescents. Specifically, reactive drug metabolites and increased oxidative stress can directly activate inflammatory and immunological pathways. Drugs are not only immunogenic because of their chemical reactivity but also because they may bind through electrostatic forces to available T-cell receptors. Redox modulation is also a key regulatory strategy in the adaptive immune system. Subtle changes in the extracellular redox status may cause profound functional changes in redox-sensitive proteins. Genetic factors that affect drug biotransformation could also be implicated in this mechanistic model of PTU-related hepatotoxicity. Further studies are needed to fully understand the pathophysiology of PTU-induced liver damage.

Propylthiouracil hepatitis: report of a case and extensive review of the literature.

Antithyroid drugs (ATDs) have been widely and effectively used for the treatment of pediatric and adult thyrotoxicosis for more than a half century. Since the very beginning of ATD use, reports of hepatic dysfunction related to propylthiouracil (PTU) therapy have been published. We describe a case of a 12-year-old girl, who, after 4 weeks of therapy for Graves disease (GD) with PTU (300 mg/day at 100 mg given three times a day), developed fatigue, fever, diarrhea, nausea, and vomiting. The initial diagnosis was "viral gastrointestinal infection". Few days after the initiation of her symptoms, the patient developed jaundice, hepatic tenderness, and dark urine. She was admitted to the hospital where, after an extensive investigation, it was found that serum glutamic oxaloacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) were elevated (2312 and 1435 IU/L, respectively), alkaline phosphatase (ALP) was 171 IU/L and total bilirubin was 12.7 mg/dL, whereas direct bilirubin was 7.6 mg/dL and prothrombin time was 23.2 s (normal ratio, < 14.5 s). Serology for hepatitis A and B was negative. The diagnosis of PTU-induced hepatitis was established. PTU was discontinued, and a treatment with prednisone (50 mg/day) and vitamin K was initiated. Four weeks after admission, her hepatic tests returned to normal. We searched the English literature and we present details of all cases with PTU-related hepatic toxicity in children and adolescents published so far. Also, we provide information regarding the mechanisms and treatment of this appalling clinical entity. Finally, after recent recommendations from American Thyroid Association (ATA) and European Thyroid Association (ETA), PTU should be administered only in the first trimester of pregnancy and in cases of drug allergy to methimazole.

Breastfeeding and antithyroid drugs: a view from within.

The aim of this communication is to provide information regarding the use of antithyroid drugs (ATD) during lactation. Three ATD are used today: propylthiouracil (PTU), methimazole (MMI) and carbimazole (CMZ). The latter is a prodrug which is bioactivated to MMI. PTU is transferred in small amounts (0.025%) into milk. These amounts were considered nonsignificant for inducing adverse effects for the suckling infant. The amount of MMI excreted in milk is equal to MMI levels in serum. Due to its lower concentrations in milk, PTU was used for decades as the treatment of choice during breastfeeding. Recent studies have demonstrated that physical development, intelligence scores and thyroid status of children whose mothers had received MMI while breastfeeding were similar to those of healthy children. These new data offered clinicians an alternative drug approach. Several hepatic dysfunction studies have been published so far. Clinical manifestations varied from mild to severe hepatic failure, liver transplantation or death. Most PTU cases were more severe, idiosyncratic and not dose related. We recommend that PTU should not be prescribed for thyrotoxicosis during lactation. MMI should be used instead, in doses up to 30 mg/day, while PTU should be used in special cases for a restricted time period.

Toxicological considerations for antithyroid drugs in children.

INTRODUCTION: Propylthiouracil (PTU), methimazole (MMI) and carbimazole are indicated for the treatment of hyperthyroidism in adult and pediatric patients. The aim of this review is to present all the relevant information regarding the use of antithyroid drugs (ATD) in pediatric thyrotoxic cases, the pediatric toxicology of ATD and the warning which has recently been issued for PTU by the FDA. AREAS COVERED: Epidemiology, diagnosis and treatment of pediatric thyrotoxicosis are all presented in this article. The authors also extensively discuss the details regarding the pharmacology, bioactivation, biodisposition, bioavailability and pharmacokinetic properties of the two main ATD (MMI and PTU). EXPERT OPINION: The FDA recently reported that use of PTU is associated with a higher risk for clinically serious or fatal liver injury compared to MMI in both adult and pediatric patients. They also found that congenital malformations were reported approximately three times more often with prenatal exposure to MMI compared with PTU and especially with the use of MMI during the first trimester of pregnancy. The authors believe that PTU should not be used in pediatric patients unless the patient is allergic to or intolerant of MMI, and there are no other treatment options available. That being said, PTU may be the treatment of choice during, and just before, the first trimester of pregnancy.

Pharmacological treatment of hyperthyroidism during lactation: review of the literature and novel data.

Antithyroid drugs (ATD) are used as a first line treatment in thyrotoxicosis. Propylthiouracil (PTU), carbimazole (CMZ) and methimazole (MMI) are available. During absorption CMZ is bioactivated to MMI. Initially, mothers were not allowed to breastfeed during treatment with ATD. Newer studies minimized the risk for mother and infant. PTU should be preferred over MMI due to its lower milk concentration. Recent studies have shown severe hepatic dysfunction for both ATD, but especially for PTU, in hyperthyroid patients. Most of those cases were idiosyncratic, not-dose related and presented a latent period of occurrence. No biomarkers could predict hepatic damage. The American Thyroid Association (ATA) has recommended that PTU should not be prescribed as the first line agent in children and adolescents. Its use might be accepted in the first trimester of pregnancy for severe thyrotoxicosis or for patients with previous MMI adverse reactions. Considering the potential harmful effects of PTU, MMI should be used instead during lactation.

Rising serum 25-hydroxy-vitamin D levels after weight loss in obese women correlate with improvement in insulin resistance.

OBJECTIVE: The objective of the study was to examine changes of 25-hydroxy-vitamin D (25OHD) and PTH blood levels 4 and 20 wk after low-calorie diet-induced weight loss. METHODS: Forty-four obese women [aged 40.6 +/- 11.4 yr, body mass index (BMI) 36.7 +/- 4.9 kg/m(2)] and 25 controls (BMI 22.9 +/- 1.5 kg/m(2)) were examined. Anthropometric and cardiometabolic parameters and 25OHD and PTH levels were determined at baseline and 4 and 20 wk after a low-calorie diet. RESULTS: At baseline, 25OHD levels were lower in obese compared with control subjects (17 +/- 6.0 vs. 23.8 +/- 8.7 ng/ml, P < 0.001), whereas no differences were found in PTH levels. In all women, a negative correlation was found between 25OHD levels and body weight (BW) (r -0.32, P < 0.001), BMI (r -0.37, P < 0.001), waist circumference (r -0.26, P < 0.05), and percent fat mass (r -0.38, P = 0.001) as determined by bioelectrical impedance analysis. The 4-wk low-calorie diet (n = 37) reduced BW and led to significant improvements in the homeostasis model assessment (HOMA) index and lipid levels. The 20-wk low-calorie diet (n = 26) resulted in reduction of BW and BMI by 10%, HOMA index (4.7 +/- 3.8 vs. 3.10 +/- 1.7, P < 0.01), and lipids levels (except high density lipoprotein cholesterol) and increase in 25OHD (15.4 +/- 6.0 vs. 18.3 +/- 5.1 ng/ml, P < 0.05), compared with baseline. PTH levels were unchanged. The increase of 25OHD levels was associated with the reduction of insulin levels and HOMA index (r -0.43, P < 0.05). CONCLUSIONS: Blood 25OHD levels were low in obese women and correlated inversely with severity measures of obesity. Weight loss of 10% after low-calorie diet increased 25OHD levels, and this increase was mainly associated with improvement of insulin resistance.