Optimal B-robust estimators for the parameters of the power Lindley distribution.

Parameters of a distribution are generally estimated by using the classical methods such as maximum likelihood (ML) and least squares (LS) estimation. However, these classical methods are very sensitive to outliers. This study, therefore, proposes the application of the optimal B-robust (OBR) estimation method, which is resistant to outliers, to estimate the parameters of power Lindley (PL) distribution. We also provide a simulation study and a real data example to compare the performance of the OBR estimators with the performances of the ML, LS, and the regression M estimators.

Assessing the Relationship Between Serum Ghrelin Levels and Metabolic Parameters and Autoimmunity in Patients with Euthyroid Hashimoto's Thyroiditis.

OBJECTIVE: Hashimoto's thyroiditis (HT) may affect metabolic parameters and increase predisposition to obesity. In this study, we aimed to assess the relationships among serum ghrelin concentrations, metabolic parameters, and thyroid autoimmunity in euthyroid HT patients. METHODS: The study included 48 euthyroid HT patients and 41 age- and sex-matched healthy controls. We assessed serum ghrelin, free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (anti-TPO), thyroglobulin antibody (anti-Tg), fasting blood glucose (FBG), insulin, lipid levels, and homeostasis model assessment insulin resistance (HOMA-IR) in all subjects. RESULTS: Sex distribution, mean age, and body mass index (BMI) were similar in HT patients and controls (female/male, 42/6 vs. 33/8, 46.8 ± 14.7 vs. 45 ± 12.5 years, 28.5 ± 6.1 vs. 28.4 ± 4.9 kg/m2, respectively; P>.05 for all). The mean waist circumference (WC) of the HT group was significantly higher than that of the control group (100.6 ± 14.6 vs. 93.2 ± 13.2 cm, P = .015). While FBG, low-density lipoprotein cholesterol (LDL-C), and triglyceride levels in the HT group were significantly higher than in the control group, insulin levels and HOMA-IR were similar. Ghrelin levels were lower in HT patients compared to controls (416.9 ± 224.4 and 689.9 ± 191.6 pg/mL, respectively; P<.001). Ghrelin levels were similar in patients with low and high anti-TPO titers. Negative correlations were observed between ghrelin levels and BMI, WC, and anti-TPO levels. Regression analysis revealed that HT was the most important predictor of ghrelin levels. CONCLUSION: Euthyroid HT is associated with a decrease in plasma ghrelin levels. Altered body fat distribution and increased anti-TPO levels do not seem to be directly involved in lower ghrelin levels in euthyroid HT patients.

Revisiting secondary amyloidosis for an inadequately investigated feature: dyslipidemia.

Secondary amyloidosis is the most frequent form of the systemic amyloidosis around the world. Data on frequency and nature of dyslipidemia in patients with secondary amyloidosis are not conclusive. We evaluated the lipid abnormalities and their association with clinical and laboratory characteristics of the patients with secondary amyloidosis. The reports of the kidney biopsies performed in our hospital were reviewed. Clinical and laboratory data of the patients with biopsy-proven secondary amyloidosis were analyzed retrospectively. A total of 102 patients were diagnosed as having secondary amyloidosis. Familial Mediterranean fever was the leading cause of secondary amyloidosis accounting for 42.2 % of the cases. The most frequent indication for kidney biopsy was the nephrotic range proteinuria. The most common clinical and laboratory characteristics at the time of the diagnosis were edema, proteinuria and impaired renal function. The frequency of the nephrotic range proteinuria and microscopic hematuria were 75.5 and 18.6 %, respectively. Dyslipidemia was found in 88 % of the cases. Serum lipids significantly correlated with estimated glomerular filtration rate (eGFR), but not with serum albumin or urine protein levels. We demonstrated that majority of the patients with secondary amyloidosis had serum lipid abnormalities. Dyslipidemia was closely associated with GFR in a manner that patients with advanced stage kidney disease had lower serum lipid levels.