Desensitization to Methimazole.

OBJECTIVE: Thionamides (methimazole and propylthiouracil) have been associated with common side effects, such as rash and pruritus, and rare but serious adverse effects, such as agranulocytosis and hepatotoxicity. Methimazole is usually the preferred thionamide for the treatment of hyperthyroidism if the patient is not planning to conceive or not in the first trimester of pregnancy, given the less frequent dosing and lower risk of hepatotoxicity. In patients who experience rash or itching when treated with methimazole, switching them to propylthiouracil is one treatment option. Here we report our experience regarding desensitization to methimazole to allow continued treatment with methimazole as an alternative management option. METHODS: We conducted a retrospective chart review of patients at a single institution who had side effects to methimazole and who were desensitized to methimazole under the supervision of an allergist. A total of 7 patients were included who experienced side effects to methimazole that did not include agranulocytosis or hepatotoxicity. RESULTS: All 7 patients were able to take methimazole for treatment of their hyperthyroidism, either for continued medical therapy or as a bridge to definitive therapy, with either surgery or radioactive iodine treatment. CONCLUSION: Under the supervision of an allergist, desensitization to methimazole is an option for treating patients who experience side effects to methimazole (excluding agranulocytosis and hepatotoxicity).

BIOTIN INTERFERENCE WITH ROUTINE CLINICAL IMMUNOASSAYS: UNDERSTAND THE CAUSES AND MITIGATE THE RISKS.

OBJECTIVE: The objectives of this report are to review the mechanisms of biotin interference with streptavidin/biotin-based immunoassays, identify automated immunoassay systems vulnerable to biotin interference, describe how to estimate and minimize the risk of biotin interference in vulnerable assays, and review the literature pertaining to biotin interference in endocrine function tests. METHODS: The data in the manufacturer's "Instructions for Use" for each of the methods utilized by seven immunoassay system were evaluated. We also conducted a systematic search of PubMed/MEDLINE for articles containing terms associated with biotin interference. Available original reports and case series were reviewed. Abstracts from recent scientific meetings were also identified and reviewed. RESULTS: The recent, marked, increase in the use of over-the-counter, high-dose biotin supplements has been accompanied by a steady increase in the number of reports of analytical interference by exogenous biotin in the immunoassays used to evaluate endocrine function. Since immunoassay methods of similar design are also used for the diagnosis and management of anemia, malignancies, autoimmune and infectious diseases, cardiac damage, etc., biotin-related analytical interference is a problem that touches every area of internal medicine. CONCLUSION: It is important for healthcare personnel to become more aware of immunoassay methods that are vulnerable to biotin interference and to consider biotin supplements as potential sources of falsely increased or decreased test results, especially in cases where a lab result does not correlate with the clinical scenario. ABBREVIATIONS: FDA = U.S. Food & Drug Administration FT3 = free tri-iodothyronine FT4 = free thyroxine IFUs = instructions for use LH = luteinizing hormone PTH = parathyroid hormone SA/B = streptavidin/biotin TFT = thyroid function test TSH = thyroid-stimulating hormone.

ADULT HYPOPHOSPHATASIA TREATED WITH TERIPARATIDE: REPORT OF 2 PATIENTS AND REVIEW OF THE LITERATURE.

OBJECTIVE: Hypophosphatasia (HPP) is a rare inherited metabolic bone disease from deficient activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). Reportedly, teriparatide (parathyroid hormone 1-34) can benefit the adult form of HPP, including fracture healing. We studied 2 women with adult HPP given teriparatide and reviewed the reports of 6 additional patients. METHODS: A 68-year-old black woman (patient 1) described low-trauma fractures and had subnormal serum alkaline phosphatase (ALP) activity. Biochemical findings were consistent with HPP. Mutation analysis revealed a heterozygous defect in exon 10 of TNSALP (ALPL). Teriparatide was injected daily for 2 years. Four years later, she fractured her right hip. Treatment was resumed for 8 months without further fractures. A 53-year-old white woman (patient 2) reported low-trauma fractures and had subnormal serum ALP. Mutation analysis revealed a heterozygous defect in exon 8 of TNSALP. She injected teriparatide daily for 2 years. One year later, bone mineral density (BMD) declined and treatment was resumed for 3 months. When she sustained a sacral fracture, teriparatide was administered for a further 18 months. RESULTS: Patient 1's serum ALP increased while receiving teriparatide and returned to baseline after its discontinuation. BMD remained unchanged, but no fractures were sustained. Patient 2's serum ALP increased, but the improvement was not sustained. Femoral neck BMD increased significantly during the first cycle, declined significantly afterwards, and was regained during a second course of teriparatide. CONCLUSION: Teriparatide shows some benefit for adult HPP. ABBREVIATIONS: ALP = alkaline phosphatase BMD = bone mineral density BSAP = bone-specific alkaline phosphatase CTX = C-telopeptide DXA = dual-energy X-ray absorptiometry FN = femoral neck HPP = hypophosphatasia LS = lumbar spine PEA = phosphoethanolamine PLP = pyridoxal 5'-phosphate PTH = parathyroid hormone SQ = subcutaneous TNSALP = tissue-nonspecific isoenzyme of alkaline phosphatase TPTD = teriparatide.

SELECTIVE HYPOALDOSTERONISM: A REVIEW.

OBJECTIVE: Selective hypoaldosteronism (SH) is a condition manifested by hyperkalemia due to low aldosterone secretion with normal cortisol. One of the obstacles in diagnosis is the awareness of the condition itself. The objective of this review is to highlight what is known about the epidemiology, pathophysiology, etiology, presentation, diagnosis, and treatment of SH. METHODS: Literature search was performed on PubMed and Ovid Medline for articles which contained hypoaldosteronism as a major topic. RESULTS: The recent literature on this topic is surprisingly limited. Few recent review articles were found, none of which were in English and less than 5 years old. Case reports and genetic literature were also included in this review, as they contain the most recent reports of SH in the literature. CONCLUSION: Awareness about SH will hopefully help physicians to identify patients at risk as well as decide on treatment if any therapy is required.

The association between glycemic control and clinical outcomes after kidney transplantation.

OBJECTIVE: To analyze the relationship between glycemic control after renal transplantation and subsequent graft function and complications. METHODS: We conducted a retrospective chart review of 202 consecutive patients undergoing kidney transplantation to analyze the association between perioperative and chronic glycemic control and clinical outcomes of rejection, infection, and hospital readmission during the first year after kidney transplantation. RESULTS: Mean in-hospital blood glucose (BG) was 157 ± 34.5 mg/dL. Mean hemoglobin A1c (HbA1c) during the first 12 months posttransplantation was 6.84 ± 1.46%. Fiftyfour patients (27%) were treated for acute or chronic rejection, 88 (44%) for infection, and 149 (74%) patients were readmitted at least once within the first year after transplantation. There were no significant differences in the risks for rejection, infection, or readmission across the 5 mean initial inpatient BG or subsequent HbA1c quintiles. In addition, there was no significant relationship between the percentage of BG measurements that fell in the "tight control" range of 80 to 110 mg/dL for each patient and any of the outcomes. CONCLUSION: We did not find an association between glycemic control (perioperative or chronic) and the outcomes of graft rejection, infection, or hospital readmission in the first 12 months after renal transplantation. Our results suggest that "near normal" glycemic targets are not necessary for managing hyperglycemia after renal transplantation.

A primer on concentrated insulins: what an internist should know.

The common insulin concentration in most preparations of insulin is 100 units per mL or U-100. Human regular U-500 insulin was the first concentrated insulin introduced and it has been available in the United States since the 1950s. Humulin R is the only human regular U-500 available on the market. Human regular U-500 is five times more concentrated than U-100 and because of its pharmacodynamic properties, works as both a basal and a bolus insulin. Human regular U500 allows for delivery of a larger insulin dose with a smaller volume leading to better absorption compared to U-100 and has traditionally been used in patients with moderate to severe insulin resistance. More recently other forms of concentrated insulin have become available and the newer concentrated insulin preparations can be used in diabetic patients with or without insulin resistance. Our intent is to provide primary care physicians with a review of the pharmacology and current literature on concentrated insulins as well as recommendations for patient selection, dose initiation, and dose adjustment.

Neurology of the pituitary.

The anterior pituitary hormones are essential for reproduction, growth, metabolic homeostasis, stress response, and adaptation to changes in the external environment. Each pituitary hormone is secreted in a distinctive pulsatile manner reflecting its regulation by the central nervous system through a complex interaction between hypothalamic neuroendocrine pathways, feedback effects from peripheral target gland hormones, and intrapituitary mechanisms. While the most common cause of a pituitary mass is an adenoma, the differential diagnosis is broad and includes pituitary hyperplasia, lymphocytic hypophysitis, craniopharyngioma among others. Patients with pituitary adenomas can be asymptomatic or present with symptoms due to mass effect, pituitary hormone dysfunction, or both. Prolactinomas represent 40% of pituitary adenomas, the majority of which are microadenomas. Hyperfunction of growth hormone and ACTH are far less common, while TSH-producing tumors are exceedingly rare. Hypopituitarism in patients with pituitary adenomas can be partial or complete. The clinical picture will depend on the type, degree, and rapidity of onset of pituitary hormone deficiency. An MRI specifically focused on the sellar region is the imaging modality of choice to detect pituitary pathology. Management of pituitary tumors ranges from observation of nonfunctioning microadenomas through medical, surgical, and radiotherapeutic approaches dependent on tumor type, function, size, and invasiveness.