Levothyroxine malabsorption or pseudomalabsorption? A question in the management of refractory hypothyroidism

PURPOSE

The levothyroxine absorption test (LT4AT) is an important tool for distinguishing hypothyroidism due to malabsorption from 'pseudomalabsorption' conditions. Our aim was to review our institution's LT4AT results and assess its role in the management of patients with refractory hypothyroidism.

METHODS

We performed a retrospective study of all patients evaluated for refractory hypothyroidism who underwent LT4AT in our tertiary center between 2014 and 2020. Its results and the impact on thyroid function management during follow-up were assessed.

RESULTS

Ten female patients were included with a mean age of 40 years (min-max: 26-62). Mean weight was 72 kg (min-max: 43-88) and baseline LT4 dosage ranged from 2.5 to 5.3 µg/kg/day. The most common causes of hypothyroidism were postsurgical in 50% (n = 5) and autoimmune in 20% (n = 2). During LT4AT, normal LT4 absorption was found in all but one individual (mean FT4 increase of 231%, min-max: 85-668). The only patient with objective LT4 absorption impairment (maximal increase of 48% by hour 5) presented also Helicobacter pylori gastritis and prior history of 'intestinal surgery' during childhood. No adverse events were reported during any of the LT4ATs. During follow-up (median 11.5 months (IQR 23)), three patients obtained euthyroidism and six had improved their hypothyroidism state.

CONCLUSIONS

The LT4AT is an effective and safe way to assess refractory hypothyroidism and provides valuable information to distinguish LT4 malabsorption from 'pseudomalabsorption'. Our data suggest that most patients with suspicious LT4 malabsorption perform normally during LT4AT. This test provides relevant information for better management of patients with refractory hypothyroidism.

MODY probability calculator utility in individuals' selection for genetic testing: Its accuracy and performance

Introduction

MODY probability calculator (MPC) represents an easy‐to‐use tool developed by Exeter University to help clinicians prioritize which individuals should be oriented to genetic testing. We aimed to assess the utility of MPC in a Portuguese cohort with early‐onset monogenic diabetes.

Methods

This single‐centre retrospective study enrolled 132 participants submitted to genetic testing between 2015 and 2020. Automatic sequencing and, in case of initial negative results, generation sequencing were performed. MODY probability was calculated using the probability calculator available online. Positive and negative predictive values (PPV and NPV, respectively), accuracy, sensitivity and specificity of the calculator were determined for this cohort.

Results

Seventy‐three individuals were included according to inclusion criteria: 20 glucokinase (GCK‐MODY); 16 hepatocyte nuclear factor 1A (HNF1A‐MODY); 2 hepatocyte nuclear factor 4A (HNF4A‐MODY) and 35 DM individuals with no monogenic mutations found. The median probability score of MODY was significantly higher in monogenic diabetes‐positive subgroup (75.5% vs. 24.2%, p < .001). The discriminative accuracy of the calculator, as expressed by area under the curve, was 75% (95% CI: 64%–85%). In our cohort, the best cut‐off value for the MODY calculator was found to be 36%, with a PPV of 74.4%, NPV of 73.5% and corresponding sensitivity and specificity of 76.2% and 71.4%, respectively.

Conclusions

In a highly pre‐selected group of probands qualified for genetic testing, the Exeter MODY probability calculator provided a useful tool in individuals' selection for genetic testing, with good discrimination ability under an optimal probability cut‐off of 36%. Further geographical and population adjustments are warranted for general use.

O-118 New insight into the genetic contribution of common variants to the development of extreme phenotypes of unexplained male infertility: a multicenter genome-wide association study

Study question

What is the contribution of the common genetic variation to the development of unexplained male infertility due to severe spermatogenic failure (SPGF)?

Summary answer

Genetic polymorphisms of key immune and spermatogenesis loci are involved in the etiology of the most severe SPGF cases, defined by Sertoli cell-only (SCO) phenotype.

What is known already

Male infertility is a rising worldwide concern that affects millions of couples. Non-obstructive azoospermia (NOA) and severe oligospermia (SO) are two extreme manifestations characterized by SPGF. A genetic cause can be established in only around 20% of affected men, with the remaining cases being classified as otherwise unexplained. To date, the genome-wide association study (GWAS) strategy, although already successfully applied in several other complex traits and diseases, was less fruitful in studies that attempted to decipher the genetic component of unexplained SPGF, mainly due to both a lack of well-powered samples in different ancestries and limitations in study design.

Study design, size, duration

We designed a GWAS for unexplained male infertility due to SPGF including a total of 1,274 affected cases and 1,951 fertile controls from the Iberian Peninsula (Spain and Portugal) and Germany. Different biostatistics and bioinformatics approaches were used to evaluate the possible effect of single-nucleotide polymorphisms (SNPs) across the whole genome in the susceptibility to specific subtypes of unexplained SPGF.

Participants/materials, setting, methods

The case cohort comprised 502 SO and 772 NOA patients, who were subdivided according to histological phenotypes (SCO, maturation arrest, and hypospermatogenesis) and the outcome of testicular sperm extraction techniques (TESE) from testis biopsies. Genotyping was performed with the GSA platform (Illumina). After quality-control and genotype imputation, 6,539,982 SNPs remained for the analysis, which was performed by logistic regression models. The datasets went through a meta-analysis by the inverse variance weighted method under fixed effects.

Main results and the role of chance

Genetic associations with SCO at the genome-wide-level of significance were identified in the major histocompatibility (MHC) class II region (rs1136759, OR = 1.80, P = 1.32E-08) and in a regulatory region of chromosome 14 nearby the vaccinia-related kinase 1 (VRK1) gene (rs115054029, OR = 3.14, P = 4.37-08). VRK1 is a relevant proliferative factor for spermatogenesis that causes progressive loss of spermatogonia when disrupted in mouse models. The role of the MHC system in SCO susceptibility was comprehensively evaluated through a validated imputation method that infers classical MHC alleles and polymorphic amino acid positions. A serine at position 13 of the HLA-DRβ1 protein (defined by the risk allele of the lead variant rs1136759) explained most of the SCO association signals within the MHC class II region. This residue is located in the binding pocket of the HLA-DR molecule and interacts directly with the presented antigen. Interestingly, position 13 of HLA-DRβ1 is the most relevant risk amino acid position for a wide spectrum of immune-mediated disorders. The HLA-DRB1*13 haplotype (which includes the serine at position 13 and represents the strongest NOA-associated marker in Asians to date) was the strongest signal amongst the classical MHC alleles in our study cohort (OR = 1.93, P = 9.90E-07).

Limitations, reasons for caution

Although the statistical power for the overall analysis was appropriate, the subphenotype analyses performed had considerably lower counts, which may influence the identification of genetic variants conferring low to moderate risk effects. Independent studies in larger SCO study cohorts should be performed to confirm our findings.

Wider implications of the findings

The molecular mechanisms underlying unexplained SPGF are largely unknown. Our data suggest a relevant role of common genetic variation in the development of SCO, the most extreme histological phenotype of NOA. SCO is characterized by the loss of germ cells and, therefore, implies a considerably higher probability of unsuccessful TESE.

Trial registration number

N/A

Semen quality is affected by HLA class I alleles together with sexually transmitted diseases

BACKGROUND

The human leukocyte antigen (HLA) locus includes several genes with key roles in antigen presentation and immune response, some of them inclusively found to be associated with non-obstructive azoospermia. Still, HLA connections to other infertility phenotypes such as semen hyperviscosity (SHV), asthenozoospermia (AST), and oligozoospermia (OLI) have been often neglected.

OBJECTIVES

In this work, we aimed to evaluate the association of HLA class I and II genes with SHV, AST, and OLI phenotypes while exploring a possible role in an adaptive immune response to sexually transmitted diseases (STD).

MATERIALS AND METHODS

Whole-exome sequencing was performed in a Portuguese cohort of 71 infertility cases and 68 controls, followed by HLA typing using a specific software-HLA*PRG:LA tool. Molecular screenings of seven STD were carried out in a subset of 72 samples (30 cases and 42 controls).

RESULTS

Statistical tests uncovered three protective alleles: HLA-A*11:01, associated with all forms of male infertility (p = 0.0006); HLA-DQB1*03:02 with SHV and OLI (P_SHV   = 0.0303, P_OLI   = 0.0153); and HLA-A*29:02 with OLI (p = 0.0355), which was found to interfere in sperm number together with HPV (p = 0.0313). Five risk alleles were also identified: two linked with SHV (HLA-B*50:01, p = 0.0278; and HLA-C*06:02, p = 0.0461), another one with both SHV and OLI (HLA-DQA1*05:01, P_SHV   = 0.0444 and P_OLI =0.0265), and two with OLI (HLA-C*03:03, p = 0.0480; and HLA-DQB1*03:01, p = 0.0499). Here, HLA-C*03:03 carriers tend to be HPV infected.

CONCLUSIONS

The application of HLA*PRG:LA tool to the study of male infertility provided novel insights for an HLA correlation with semen quality, namely among SHV and OLI phenotypes. The discovery of an HLA-A*29:02/HPV crosstalk, together with former reports of HLA alleles conferring resistance-susceptibility to diverse human pathogens, raises the hypothesis of a mechanistic link between male infertility, HLA polymorphism, and host response to STD.

Severity of disease scoring systems and mortality after non-cardiac surgery

Background

Mortality after surgery is frequent and severity of disease scoring systems are used for prediction. Our aim was to evaluate predictors for mortality after non-cardiac surgery.

Methods

Adult patients admitted at our surgical intensive care unit between January 2006 and July 2013 was included. Univariate analysis was carried using Mann–Whitney, Chi-square or Fisher's exact test. Logistic regression was performed to assess independent factors with calculation of odds ratio and 95% confidence interval (95% CI).

Results

4398 patients were included. Mortality was 1.4% in surgical intensive care unit and 7.4% during hospital stay. Independent predictors of mortality in surgical intensive care unit were APACHE II (OR = 1.24); emergent surgery (OR = 4.10), serum sodium (OR = 1.06) and FiO₂ at admission (OR = 14.31). Serum bicarbonate at admission (OR = 0.89) was considered a protective factor. Independent predictors of hospital mortality were age (OR = 1.02), APACHE II (OR = 1.09), emergency surgery (OR = 1.82), high-risk surgery (OR = 1.61), FiO₂ at admission (OR = 1.02), postoperative acute renal failure (OR = 1.96), heart rate (OR = 1.01) and serum sodium (OR = 1.04). Dying patients had higher scores in severity of disease scoring systems and longer surgical intensive care unit stay.

Conclusion

Some factors influenced both surgical intensive care unit and hospital mortality.

[Severity of disease scoring systems and mortality after non-cardiac surgery]

BACKGROUND

Mortality after surgery is frequent and severity of disease scoring systems are used for prediction. Our aim was to evaluate predictors for mortality after non-cardiac surgery.

METHODS

Adult patients admitted at our surgical intensive care unit between January 2006 and July 2013 was included. Univariate analysis was carried using Mann-Whitney, Chi-square or Fisher's exact test. Logistic regression was performed to assess independent factors with calculation of odds ratio and 95% confidence interval (95% CI).

RESULTS

4398 patients were included. Mortality was 1.4% in surgical intensive care unit and 7.4% during hospital stay. Independent predictors of mortality in surgical intensive care unit were APACHE II (OR=1.24); emergent surgery (OR=4.10), serum sodium (OR=1.06) and FiO₂ at admission (OR=14.31). Serum bicarbonate at admission (OR=0.89) was considered a protective factor. Independent predictors of hospital mortality were age (OR=1.02), APACHE II (OR=1.09), emergency surgery (OR=1.82), high-risk surgery (OR=1.61), FiO₂ at admission (OR=1.02), postoperative acute renal failure (OR=1.96), heart rate (OR=1.01) and serum sodium (OR=1.04). Dying patients had higher scores in severity of disease scoring systems and longer surgical intensive care unit stay.

CONCLUSION

Some factors influenced both surgical intensive care unit and hospital mortality.

Postoperative Haematocrit and Outcome in Critically Ill Surgical Patients

INTRODUCTION

Haematocrit has been studied as an outcome predictor. The aim of this study was to evaluate the correlation between low haematocrit at surgical intensive care unit admission and high disease scoring system score and early outcomes.

MATERIAL AND METHODS

This retrospective study included 4398 patients admitted to the surgical intensive care unit between January 2006 and July 2013. Acute physiology and chronic health evaluation and simplified acute physiology score II values were calculated and all variables entered as parameters were evaluated independently. Patients were classified as haematocrit if they had a haematocrit < 30% at surgical intensive care unit admission. The correlation between admission haematocrit and outcome was evaluated by univariate analysis and linear regression.

RESULTS

A total of 1126 (25.6%) patients had haematocrit. These patients had higher rates of major cardiac events (4% vs 1.9%, p < 0.001), acute renal failure (11.5% vs 4.7%, p < 0.001), and mortality during surgical intensive care unit stay (3% vs 0.8%, p < 0.001) and hospital stay (12% vs 5.9%, p < 0.001).

DISCUSSION

A haematocrit level < 30% at surgical intensive care unit admission was frequent and appears to be a predictor for poorer outcome in critical surgical patients.

CONCLUSION

Patients with haematocrit had longer surgical intensive care unit and hospital stay lengths, more postoperative complications, and higher surgical intensive care unit and hospital mortality rates.

Complete genome sequence of two rabbit hemorrhagic disease virus variant b isolates detected on the Iberian Peninsula

We report the complete genome sequences of two isolates (RHDV-N11 and CBVal16) of variant rabbit hemorrhagic disease virus (RHDVb). Isolate N11 was detected in young domestic animals during a rabbit hemorrhagic disease (RHD) outbreak that occurred in 2011 on a rabbit farm in Navarra, Spain, while CBVal16 was isolated from a wild rabbit found dead in Valpaços, Northern Portugal, a year later. The viral sequences reported show 84.8-85.1 % and 78.3-78.5 % identity to RHDVAst/89 and RCV-A1 MIC-07, representative members of the pathogenic genogroup 1 RHDV and apathogenic rabbit calicivirus, respectively. In comparison with other RHDV isolates belonging to the previously known genogroups 1-6, RHDVb shows marked phenotypic differences, as it causes disease preferentially in young rabbits under 40 days of age and shows modified red blood cell agglutination profiles as well as antigenic differences that allow this variant to escape protection by the currently available vaccines.

Unexplained elevated midtrimester maternal serum levels of alpha fetoprotein, human chorionic gonadotropin, or low unconjugated estriol: recurrence risk and association with adverse perinatal outcome

OBJECTIVE

To determine if women experiencing an unexplained elevated maternal serum alpha fetoprotein (MSAFP; > or =2.0 MoM) or human chorionic gonadotropin (hCG; > or =2.0 MoM), or low unconjugated estriol (E3; < or =0.5 MoM) in one pregnancy are at increased risk for similar results in a subsequent pregnancy, and to determine if recurrence of these analyte extremes is associated with adverse perinatal outcome.

METHODS

We identified all women delivering two consecutive singleton pregnancies at one hospital between 1992-1997 for whom second trimester trisomy 21 serum screen was performed in each pregnancy. All screens were performed in a single laboratory. Each pregnancy delivered after 20 weeks and had gestational age confirmed by ultrasound prior to 24 weeks. Subjects were excluded if a fetal anomaly or aneuploidy was present. Adverse outcomes included abruption, oligohydramnios, preeclampsia, preterm membrane rupture, preterm delivery, stillbirth, birthweight <10th centile, and admission to neonatal intensive care unit (NICU).

RESULTS

A total of 538 women had 1,076 pregnancies meeting inclusion criteria; 12/515 (2.3%) of women with a normal MSAFP, 28/470 (6.0%) with a normal hCG, and 11/504 (2.2%) with a normal E3 in the first pregnancy had an anomalous result for the respective analyte in the second pregnancy. In contrast, only 4/23 (17.4%) patients with an elevated MSAFP (P = 0.003), 14/44 (31.8%) with an elevated hCG (P < 0.001), and 2/10 (20.0%) with a low E3 (P < 0.025) in the first pregnancy had the same analyte anomaly recur in the second pregnancy. The odds ratios for recurrent elevated MSAFP, hCG, and low E3 were 7.5, 5.3, and 9.2, respectively. Adverse perinatal outcomes occurred with similar frequency, regardless of MSAFP, hCG, or E3 results in consecutive pregnancies, using women with normal MSAFP, hCG, and E3 results in one or both pregnancies as controls.

CONCLUSIONS

Women experiencing an anomalous serum analyte in one pregnancy are at significant risk to experience the same analyte result in a subsequent pregnancy.

Development of compensatory thermogenesis in response to overfeeding in hypothyroid rats

Intact or surgically thyroidectomized (Tx) adult male Wistar rats, weighing 150-200 g, were fed a standard chow diet (approximately 1.8 Cal/g) or a high calorie (approximately 3.8 Cal/g) diet (cafeteria diet) for up to 30 days. Daily energy intake was about 5-fold higher in the rats fed the cafeteria diet regardless of their thyroid status. The cafeteria diet caused the retroperitoneal white fat pad to increase by approximately 2-fold, the volume of isolated white adipocytes to increase by 2-fold, and the total body fat to increase by a factor of approximately 3, again regardless of thyroid status. It also increased basal metabolic rate by about 20% in intact rats and by about 50% in Tx rats. The brown fat thermal response to norepinephrine (NE) infusion was approximately 2-fold increased in the intact rats fed the cafeteria diet. However, in the Tx rats, the brown fat thermal response to NE was blunted regardless of the dietary regimen adopted. In both intact and Tx rats, the cafeteria diet increased total brown fat mitochondria, uncoupling protein percentage, and total brown fat uncoupling protein by about 3-, 2-, and 5-fold, respectively. Serum leptin levels also increased approximately 4-fold in intact rats fed the cafeteria diet. However, in Tx rats, leptin levels did not change significantly during overfeeding. In conclusion, hypothyroidism caused the brown fat to become unresponsive to NE, even after 1 month on the cafeteria diet. However, these rats were able to increase basal metabolic rate and, as assessed by several different parameters, did not gain fat beyond that observed in intact controls kept on a similar overfeeding schedule.