A new strategy to estimate levothyroxine requirement after total thyroidectomy for benign thyroid disease.

BACKGROUND: The current approach for calculating the starting dose of levothyroxine (LT4) after total thyroidectomy is based on the patient's body weight (BW). The aim of the study was to identify the major predictive factors of LT4 requirement and to elaborate a new method to improve the accuracy of the LT4 starting dose after total thyroidectomy. METHODS: The study consists of two parts. The first part consisted of the retrospective identification of 92 adult patients (retrospective cohort) who had undergone a total thyroidectomy for benign disease and who had begun LT4 treatment at a dose of 1.6 µg/kg/day. Adjustments to optimize the LT4 dose were then performed at the post-surgery follow-up on the basis of serum thyrotropin (TSH) levels. The results of this retrospective analysis were used to formulate a nomogram for a proper calculation of the LT4 starting dose that was then used prospectively in the second part of the study on 31 consecutive patients (prospective cohort). RESULTS: At the first follow-up, 37 (40%) patients from the retrospective cohort were euthyroid. Univariate analysis indicated significant correlations between the optimal dose of LT4 and BW, body mass index (BMI), age, preoperative mean corpuscular volume, and free triiodothyronine (fT3). The optimal dose of LT4, analyzed for BMI and age, showed an inverse relationship with these two parameters, and ranged from 1.4 to 1.8 µg/kg/day. In the prospective cohort, the use of an age- and BMI-related nomogram improved the prediction of the optimal LT4 starting dose, with 68% of patients being euthyroid at the first follow-up compared to 41% of patients reported to have reached euthyroid state using the best strategy proposed in the literature. CONCLUSIONS: This study confirms that BW is not the only variable for predicting LT4 requirement, as it decreases with the increase in age and BMI, probably due to the relative decrease of lean body mass. A new correlation between optimal dose and presurgical levels of fT3 and mean corpuscular volume was observed. We propose an easy and more efficient method of calculating LT4 starting dose after total thyroidectomy for benign disease.

The role of adrenal scintigraphy in the diagnosis of subclinical Cushing's syndrome and the prediction of post-surgical hypoadrenalism.

BACKGROUND: Management of subclinical Cushing's syndrome (SCS) remains controversial; it is not possible to predict which patients would benefit from adrenalectomy. In the present study we aimed to evaluate the role of adrenocortical scintigraphy (ACS) in the management of patients with SCS. METHODS: The medical records of 33 consecutive patients with adrenal "incidentaloma" and proven or suspected SCS who underwent (131)I-19-iodocholesterol ACS between 2004 and 2010 were reviewed. Sixteen underwent laparoscopic adrenalectomy (surgical group-S-group) and 17 were medically managed (medical group-M-group). Follow-up evaluation was obtained by outpatient consultation. RESULTS: Overall 25 patients (15 in the S-group and 10 in the M-group) had concordant unilateral uptake at ACS (ACS+). In the S-group, the mean follow-up duration was 30.9 ± 16.1 months and, irrespective of the presence of hormonal diagnosis of SCS, in patients who were ACS+ adrenalectomy resulted in a significant increase in HDL cholesterol and decreases in body mass index, glycemia, and blood pressure (BP). One patient reduced antihypertensive medication and three others were able to discontinue it altogether. Prolonged postoperative hypoadrenalism (PH) occurred in 14 patients in the S-group. The overall accuracy in predicting PH was 93.7 % for ACS and 68.7 % for laboratory findings. In the M-group, the mean follow-up duration was 31.5 ± 26.3 months and no patient developed overt Cushing's syndrome, although ACS+ patients experienced a worsening in glycemia and diastolic BP. CONCLUSIONS: Adrenal scintigraphy seems the most accurate diagnostic test for SCS. It is able to predict the metabolic outcome and the occurrence of PH, identifying the patients who could benefit from adrenalectomy irrespective of hormonal diagnosis.

Post-surgery severe hypocalcemia in primary hyperparathyroidism preoperatively treated with zoledronic acid.

Zoledronic acid is a newly FDA-approved bisphosphonate for the treatment of hypercalcemia of malignancy. Although the safety and efficacy of this drug in treating hypercalcemia associated with hyperparathyroidism have not yet been established in clinically controlled trials, its off-label use is not uncommon. We describe a patient with primary hyperparathyroidism treated with zoledronic acid who developed severe postoperative hypocalcemia. A 64-yr-old woman was admitted with severe hypercalcemia. She was treated with rehydration, calcitonin, methylprednisolone, furosemide as well as 4 mg/day of zoledronic acid for two consecutive days. Primary hyperparathyroidism caused by a right inferior parathyroid lesion was diagnosed. While awaiting surgery, she continued furosemide, methylprednisolone and hydration: after one week, serum calcium had fallen to such a low level that a short-term calcium carbonate supplementation was required. Three weeks after admission, the patient underwent selective right inferior parathyroidectomy, followed by reduction of PTH. During the postoperative period the patient presented severe hypocalcemia resistant to the usual treatment. Serum calcium levels returned to normal three months after surgery. The severity of hypocalcemia and the resistance to conventional treatments suggest that the effect of hungry bone syndrome could be worse in patients treated with bisphosphonates in the preoperative phase.