Intravenous Thyroxine Administration in Hospitalized Patients, a Common but Unreported Practice: a Single Institution Recent Experience

Background: Intravenous levothyroxine (IVT4) is FDA-approved for the treatment of myxedema coma (ME). ATA guidelines also acknowledge other rare situations, mostly such where oral/enteral access is compromised for prolonged periods, in which IVT4 may be appropriate. We noticed that at our hospital, IVT4 is administered more frequently than expected. Aim of study: To assess the extent of IVT4 administration, the indications for such a treatment, and its outcome at a tertiary facility. Study design and Methods: A retrospective study of IVT4 administered to adult inpatients at Tel Aviv-Sourasky Medical Center between January 2017 and July 2020. A list of dispensed T4 vials during the period of interest was generated from the hospital pharmacy computerized database. Patients’ charts were searched for relevant clinical and laboratory data. Results: 107 patients (62 W/45 M), age 62.5±17.3 y (range 20-97) received IV T4, in the course of 113 hospitalizations. 94 subjects had primary hypothyroidism (PH), 10 had central hypothyroidism, while 3 subjects had no documented evidence of hypothyroidism. ME was likely in only 4 cases (3.5%). The leading stated indication for IVT4 was profound hypothyroidism in 57 instances (50.4%), jeopardized enteral route in 11 (9.7%), while no clear or justifiable indication was found in 39 cases (34.5%). An official endocrine consult backed treatment 74 times (65.5%). In subjects with PH, median serum TSH prior to treatment was 36.4 mIU/L (IQR 8-42), while free T4 was 0.4 ng/dl (IRQ 0.22-0.61, normal 0.8-1.7). In subjects with no ME, altered consciousness was present in 19%, bradycardia in 6.3% and 4.5% were hypothermic. The median initial dose of IV-T4 was 150 μg (range 20-500). Repeated administrations ranged from 1 to 29 times, with a median cumulative dose of 250 μg (IQR 150-400, range 20-3300). We could not identify adverse events directly attributable to IV-T4. Of the 113 admissions, 61 ended in patient’s recovery and discharge (54%), 22 (19.5%) in transfer to a rehab or nursing facility, while there were 30 cases of death (26.5%). Only one of the 4 patients with presumed ME died. In a logistic regression model, that also included age, gender, and ICU admission, the only variable that significantly predicted death was a need for artificial ventilation (OR:27.8, CI 3.5-189). In contrast, free T4, TSH, hospitalization length, altered consciousness, and other potential variables, were excluded from the equation. Conclusions: IVT4 administration is a common practice at our hospital. In a small minority of cases (13.2%), it is given for approved clinical conditions, while in all the others it appears to be unjustified. Reports on this practice are all but absent from the literature. Studies from other institutions are needed to determine its global extent, safety, and efficacy. Until it is proven safe and cost-effective, greater caution should be exercised before allowing it.

A Cross Sectional Analysis of the Prevalence of Co-Morbidities in Older Transgender Individuals Receiving Hormone Affirming Therapy in Comparison With the General Population

Background: Transgender individuals feel an incongruity between the assigned gender at birth and their gender identity. Because the prevalence of cardiovascular risk factors and morbidity associated with cross-sex hormonal therapy is not well established, particularly in the older transgender population, we set out to compare it to that of the general population. Methods: Data were collected from medical records of transgender patients treated in the Endocrine Institute at the Tel Aviv-Sourasky Medical Center until October 2018. Data from the Israel National Health Survey INHIS-3 2013-2015 were used as reference. Results: 104 (75 transgender women and 29 transgender men) patients over 35 y were identified. The median follow up time was 3 y (1-6.1). Transgender women had a high standardized prevalence rate (SPR) of overweight, smoking and engaging in physical exercise, but not of dyslipidemia compared with cisgender men and women. The SPR for overweight was high in transgender males compared with cisgender men and women. The SPR for smoking and dyslipidemia was high in transgender men compared with cisgender women but not men. Depression and anxiety were markedly increased in transgender women compared with cisgender men [SPR 5.5 (95% CI 3.3-8.5), p<0.001] and women [SPR 2.8 (95% CI 1.7-4.3), p<0.001] in the control population. The SPR of hypertension, diabetes and cerebrovascular disease was not elevated among transgender patients. Conclusions: The prevalence of cardiovascular risk factors but not cardiovascular morbidity was higher in the transgender patients compared with the general population. Further studies including a larger population and a longer follow up time are needed to better assess the impact of a high prevalence of risk factors on cardiovascular morbidity on the long run.

Insulin-degrading enzyme higher in subjects with metabolic syndrome

Metabolic syndrome (MS) is comprised of a cluster of abnormalities in glucose, lipid, and vascular homeostasis, which is most commonly linked to abdominal obesity. MS heralds increased risk for development of diabetes and is linked to impairment in insulin signaling. Insulin-degrading enzyme (IDE) is one of the mechanisms through which insulin blood levels are maintained. It has been previously suggested that controlling IDE levels could provide yet another potential therapeutic approach in diabetes. Here we aim to investigate whether changes in serum IDE levels correlate with the severity of MS. Using a highly sensitive ELISA assay of active IDE in human serum, we found a strong correlation between circulating IDE levels and circulating levels of triglycerides, insulin, and c-peptide and an inverse correlation with HDL cholesterol (HDLc). Serum IDE levels were higher in MS subjects than in control subjects. Hence, circulating IDE may serve as a tool to identify subjects with abnormal insulin metabolism, possibly those with MS that are at risk to develop diabetes.

SAT-180 Adrenocortical Carcinoma - A Tertiary Center’s Recent 5-Year Experience

BACKGROUND: Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with poor prognosis. The aim of this study was to characterize patients diagnosed with ACC at a single center between 2014-2019.

METHODS: We retrospectively reviewed data regarding demographics, tumor characteristics and functionality, treatment and survival.

RESULTS: The study cohort included 27 subjects (56% females), followed for 27±10.6 months. The mean age at diagnosis was 49.4±9 years. Co-morbidities at presentation included hypertension (63%), diabetes mellitus (22%) and dyslipidemia (26%). 74.1% of tumors were functioning – of which 85% were cortisol-secreting and 15% androgen-secreting. Aldosterone was secreted additionally in 15%. ENSAT stage at diagnosis was stage 1 in 15%, stage 2 in 35%, stage 3 in 12% and stage 4 in 38%. Eighty-nine % of patients underwent surgery. Treatment with mitotane was initiated in 82% of patients, reaching a mean maximal dose of 3.3 ±0.4 grams/day. Chemotherapy and/or radiation were given in 37% and 22%, respectively. Several patients (14.8%) had a second primary cancer, diagnosed before ACC in 75%. Progression was observed in 48% of patients, with a progression-free survival of 8.3±6.6 months. Thirty-five % of patients died during follow up, time to death was 12.8±0.4 months. Twenty two % of patients survived over 30 months after diagnosis. KI67 above 20% or stage above 2 negatively affected survival.

CONCLUSIONS: ACC remains a rare disease with a poor prognosis. However, it is a heterogeneous disease, with some patients achieving survival of over 30 months after diagnosis. Further characterization of this population may improve our understanding of the biology and treatment of this rare disease.

MON-194 Phaeochromocytoma-Paraganglioma (PPGL): Post-Operative Hypotension Is a Vanishing Phenomenon

Background: Treatment of hemodynamic instability in patients with PPGL in the intra-and postoperative periods is challenging. Persistent postoperative hypotension is a common and serious complication, reportedly occurring in 30-60% of PPGL patients. This phenomenon reflects 1) high doses of pre-operative antihypertensive drugs; 2) low intravascular volume secondary to chronic catecholamine-induced vasoconstriction with pressure natriuresis; 3) the sudden drop in circulating catecholamines after surgery. It has been shown that tumor size and preoperative levels of catecholamines are directly related to the need for treatment with vasopressor agents in the early period after tumor removal. The aim of this study was to evaluate the efficacy and safety of the current perioperative treatment protocol for PPGL used in our Institute. Methods: We retrospectively reviewed the rate of hemodynamic instability and postoperative hypotension in relation to catecholamine levels, and the efficiency of preoperative pharmacological preparation in consecutive patients with PPGL treated between 2000-2019. Results: There were 39 patients (F/M 19/20; mean age 50.4 ±16.5 years) 33 of which had adrenal lesions and 6 had extra-adrenal tumors. Mean tumor size was 3.9 ±2.2 cm. Median metanephrine and normetanephrine levels were 5 and 10 fold the upper limit of the normal range respectively. All patients were treated with α-blockade (phenoxybenzamine-17, mean dose 60±38 mg/day; doxazosin-22; mean dose 9.6±6.1mg/day) along with β- blockade, and high sodium diet and IV saline 24 hours before the operation. The length of the preoperative preparation period was 3.4±2 weeks. Within the first 24-48 hours from surgery, no episodes of hypotension (<90 mmHg systolic pressure) were recorded. Mean systolic BP was 121 ±14 (range 95-150) with a mean diastolic BP of 70 ±11 (range 89-46). In contrast, intraoperative hypotension occurred in 22% of the patients; and BP surge occurred in 36% of patients, mostly during tumor manipulation. There were no differences between subjects with and without such BP rises/falls in terms of pre/post- surgical BP, catecholamine levels or type of medical treatment. Conclusion: In contrast with older literature and previous reports, the patients in our cohort did not experience postoperative hypotension. This is most likely due to tight BP control while avoiding pre-operative hypotension, and adequate volume control. We propose that proper preoperative management in the modern era can drastically minimize intraoperative hemodynamic instability and post-operative hypotension.

Effects of a typical acute oral calcium load on arterial properties and endothelial function in healthy subjects

BACKGROUND/OBJECTIVES

Often recommended, calcium supplements have been incriminated as increasing the risk of cardiovascular events, whereas dietary calcium has generally been exonerated. As a first step to address the vascular safety of such dietary measures at the clinical nutritionist toolbox, we sought to determine and compare the acute effects of a typical oral calcium load, provided either as a supplement or as food, on vascular parameters assessed noninvasively in healthy subjects.

SUBJECTS/METHODS

In this acute, cross-over, random-order intervention, 11 young and healthy vitamin D-sufficient volunteers (8 women/3 men, 33±6.1 years, body mass index 22.6±2.3 kg/m(2)), ingested 600 mg of calcium twice, once as calcium citrate and the other time from dairy products. Biochemical, vascular and hemodynamic parameters, before and 2 h after each challenge, were compared. Arterial stiffness was studied by measuring pulse wave velocity, augmentation index and large (C1) and small (C2) arterial compliance. Endothelial function was assessed by flow-mediated dilation (FMD).

RESULTS

Despite effective calcium loading accompanied by a significant 60% parathyroid hormone level reduction on both occasions, there were no clinically significant changes in the vascular parameters neither in comparison with baseline, nor between the studies. A decrease in heart rate with no change in cardiac output was noticed after the supplement.

CONCLUSIONS

An effective calcium load has no clinically significant untoward effect on the vascular properties of young healthy subjects, regardless of its source. Additional studies should determine whether this holds true for chronic calcium supplementation, particularly in subjects with a priori vascular impairment.

Differential regulation of the HepG2 and adipocyte/muscle glucose transporters in 3T3L1 adipocytes. Effect of chronic glucose deprivation

Glucose transport in 3T3L1 adipocytes is mediated by two facilitated diffusion transport systems. We examined the effect of chronic glucose deprivation on transport activity and on the expression of the HepG2 (GLUT 1) and adipocyte/muscle (GLUT 4) glucose transporter gene products in this insulin-sensitive cell line. Glucose deprivation resulted in a maximal increase in 2-deoxyglucose uptake of 3.6-fold by 24 h. Transport activity declined thereafter but was still 2.4-fold greater than the control by 72 h. GLUT 1 mRNA and protein increased progressively during starvation to values respectively 2.4- and 7.0-fold greater than the control by 72 h. Much of the increase in total immunoreactive GLUT 1 protein observed later in starvation was the result of the accumulation of a non-functional or mistargeted 38 kDa polypeptide. Immunofluorescence microscopy indicated that increases in GLUT 1 protein occurred in presumptive plasma membrane (PM) and Golgi-like compartments during prolonged starvation. The steady-state level of GLUT 4 protein did not change during 72 h of glucose deprivation despite a greater than 10-fold decrease in the mRNA. Subcellular fractionation experiments indicated that the increased transport activity observed after 24 h of starvation was principally the result of an increase in the 45-50 kDa GLUT 1 transporter protein in the PM. The level of the GLUT 1 transporter in the PM and low-density microsomes (LDM) was increased by 3.9- and 1.4-fold respectively, and the GLUT 4 transporter content of the PM and LDM was 1.7- and 0.6-fold respectively greater than that of the control after 24 h of glucose deprivation. These data indicate that newly synthesized GLUT 1 transporters are selectively shuttled to the PM and that GLUT 4 transporters undergo translocation from an intracellular compartment to the PM during 24 h of glucose starvation. Thus glucose starvation results in an increase in glucose transport in 3T3L1 adipocytes via a complex series of events involving increased biosynthesis, decreased turnover and subcellular redistribution of transporter proteins.

Differential regulation of two distinct glucose transporter species expressed in 3T3-L1 adipocytes: effect of chronic insulin and tolbutamide treatment

The HepG2-type glucose transporter (HepG2-GT) is expressed in 3T3-L1 fibroblasts and adipocytes. In contrast, the acutely insulin-regulatable glucose transporter (IRGT) is expressed only in the adipocytes. In the present study, the expression of the IRGT was shown to increase in parallel with the acquisition of acutely insulin-stimulated glucose uptake during differentiation of these cells, whereas the level of the HepG2-GT decreased during the course of differentiation in parallel with a decline in basal glucose uptake. We examined the effects of chronic insulin and tolbutamide treatment on glucose transporter activity in conjunction with the expression of these two glucose transporter species in 3T3-L1 adipocytes. Treatment of adipocytes with insulin, tolbutamide, or both agents in combination increased 2-deoxyglucose uptake, HepG2-GT protein, and HepG2-GT mRNA levels in parallel. The effect of combined insulin/tolbutamide administration on these three parameters was greater than the effect of either treatment alone. In contrast, these treatments either had no significant effect or decreased levels of IRGT protein and mRNA. We conclude that chronic treatment of 3T3-L1 adipocytes with insulin or tolbutamide increases glucose uptake primarily by means of a selective increase in the expression of the HepG2-GT. We suggest that part of the in vivo hypoglycemic effect of insulin and sulfonylureas may involve an increased expression of the HepG2-GT.

Failure of nocturnal hypoglycemia to cause fasting hyperglycemia in patients with insulin-dependent diabetes mellitus

To test the hypothesis that nocturnal hypoglycemia causes fasting hyperglycemia (the Somogyi phenomenon) in patients with insulin-dependent diabetes mellitus, we studied 10 patients, who were on their usual therapeutic regimens, from 10 p.m. through 8 a.m. on three nights. On the first night, only a control procedure was performed (blood sampling only); on the second night, hypoglycemia was prevented (by intravenous glucose infusion, if necessary, to keep plasma glucose levels above 100 mg per deciliter [5.6 mmol per liter]); and on the third night, hypoglycemia was induced (by stepped intravenous insulin infusions between midnight and 4 a.m. to keep plasma glucose levels below 50 mg per deciliter [2.8 mmol per liter]). After nocturnal hypoglycemia was induced (36 +/- 2 mg per deciliter [2.0 +/- 0.1 mmol per liter] [mean +/- SE] from 2 to 4:30 a.m.), 8 a.m. plasma glucose concentrations (113 +/- 18 mg per deciliter [6.3 +/- 1.0 mmol per liter]) were not higher than values obtained after hypoglycemia was prevented (182 +/- 14 mg per deciliter [10.1 +/- 0.8 mmol per liter]) or those obtained after blood sampling only (149 +/- 20 mg per deciliter [8.3 +/- 1.1 mmol per liter]). Indeed, regression analysis of data obtained on the control night indicated that the 8 a.m. plasma glucose concentration was directly related to the nocturnal glucose nadir (r = 0.761, P = 0.011). None of the patients was awakened by hypoglycemia. Scores for symptoms of hypoglycemia, which were determined at 8 a.m., did not differ significantly among the three studies. We conclude that asymptomatic nocturnal hypoglycemia does not appear to cause clinically important fasting hyperglycemia in patients with insulin-dependent diabetes mellitus on their usual therapeutic regimens.