[A case of thyreotoxic hypokalaemic periodic paralysis in a white male]. / Thyreotoxische hypokaliëmische periodieke paralyse bij een blanke man.

BACKGROUND: Thyreotoxic hypokalaemic periodic paralysis (THPP) is a rare and potentially life-threatening syndrome. It principally affects men of East-Asian origin and has rarely been described in a white person. CASE DESCRIPTION: A 34-year-old Dutch man, suffering from Graves' disease, presented with weakness in his lower limbs. Laboratory investigation showed severe hypokalaemia (1.8 mmol/l) and increased creatinine kinase levels. An electrocardiogram showed atrial fibrillation with a prolonged QTc-interval. The patient was admitted, cardiac rhythm was monitored, and he received potassium supplements. Laboratory investigation of thyroid function showed thyrotoxicosis. The patient was treated with propranolol and thiamazol. At follow-up, thyroid function, potassium levels and muscle strength had normalized. CONCLUSION: Hypokalaemia due to thyrotoxicosis should be considered in cases of unexplained paralysis. The treatment of THPP consists of treating for hyperthyroidism plus propranolol. Since the hypokalaemia is self-limiting, potassium supplementation is only necessary in cases of rhythm disturbances or cardiac-conduction disturbances. Despite adequate treatment, there is a risk of recurrence. Regular monitoring is indicated until euthyroidism is achieved.

Autonomic nervous system function in chronic exogenous subclinical thyrotoxicosis and the effect of restoring euthyroidism.

CONTEXT: Knowledge on the relationship between the autonomic nervous system and subclinical hyperthyroidism is mainly based upon cross-sectional studies in heterogeneous patient populations, and the effect of restoration to euthyroidism in subclinical hyperthyroidism has not been studied. OBJECTIVE: We investigated the long-term effects of exogenous subclinical hyperthyroidism on the autonomic nervous system and the potential effects of restoration of euthyroidism. DESIGN: This was a prospective single-blinded, placebo-controlled, randomized trial. SETTING: The study was performed at a university hospital. PATIENTS: A total of 25 patients who were on more than 10-yr TSH suppressive therapy after thyroidectomy was examined. INTERVENTION: Patients were studied at baseline and subsequently randomized to a 6-month thyroid hormone substitution regimen to obtain either euthyroidism or maintenance of the subclinical hyperthyroid state. MAIN OUTCOME MEASURES: Urinary excretion of catecholamines and heart rate variability were measured. Baseline data of the subclinical hyperthyroidism patients were compared with data obtained in patients with hyperthyroidism and controls. RESULTS: Urinary excretion of norepinephrine and vanillylmandelic acid was higher in the subclinical hyperthyroidism patients compared with controls and lower compared with patients with overt hyperthyroidism. Heart rate variability was lower in patients with hyperthyroidism, intermediate in subclinical hyperthyroidism patients, and highest in the healthy controls. No differences were observed after restoration of euthyroidism. CONCLUSIONS: Long-term exogenous subclinical hyperthyroidism has effects on the autonomic nervous system measured by heart rate variability and urinary catecholamine excretion. No differences were observed after restoration to euthyroidism. This may indicate the occurrence of irreversible changes or adaptation during long-term exposure to excess thyroid hormone that is not remedied by 6-month euthyroidism.

Survival and death causes in differentiated thyroid carcinoma.

BACKGROUND: Survival studies in differentiated thyroid carcinoma (DTC) may be biased because they have been performed in heterogeneous populations. In addition, specific death causes in DTC have not been documented well in the literature. AIMS: The aim of our study was to investigate survival and specific death causes in a homogeneous cohort of DTC patients. PATIENTS: Patients included 366 consecutive patients with DTC who had all been treated according to the same protocol for initial therapy and follow-up. METHODS: Prognostic factors for DTC-related death were analyzed by univariate Cox regression analysis, followed by stepwise multivariate Cox regression analysis. Standardized mortality rates (SMR) were calculated using normal mortality rates for the entire Dutch population. RESULTS: During follow-up of 8.3 +/- 4.6 yr, 82 patients (22.4%) died. At multivariate Cox-regression analysis, tumor stage T4, distant metastases, and advanced age were associated with an increased relative risk for DTC-related death. SMR for the entire group was 2.32. This could be explained by increased SMR in patients with stage T4, distant metastases, or advanced age. Death causes could be verified in 80 patients: 52 died of DTC, 28 due to other causes. Ten of the 20 patients with stage T1-3M0 died from thyroid carcinoma. CONCLUSION: Relative risk for thyroid cancer-related death and SMR are significantly increased in patients with stage T4 and M1 or advanced age. Although death risk is not increased in T1-3 M0 patients, DTC contributed significantly to mortality in all patient categories.

Does radioiodine therapy have disadvantageous effects in non-iodine accumulating differentiated thyroid carcinoma?

BACKGROUND: Although radioiodine therapy in differentiated thyroid carcinoma without radioiodine accumulation has not been considered harmful, increased thyrotrophin levels during thyroxine withdrawal without the benefit of radiotoxicity as well as the selection of de-differentiated cells may have disadvantageous effects on tumour course. OBJECTIVE: We therefore analysed retrospectively the effects of radioiodine therapy on the course of serum thyroglobulin levels as a tumour marker in patients with progressive residual or metastatic differentiated thyroid carcinoma, with or without radioiodine accumulation on post-therapeutic whole body scintigraphy. PATIENTS AND METHODS: Patients who had undergone radioiodine therapies with sufficient pre- and post-therapy thyroglobulin measurements to allow for regression analysis and not preceded or followed by other treatment modalities within a 1-year interval were selected. All patients had undergone total thyroidectomy and ablative therapy. Thirty-nine patients and radioiodine therapies were included (10 males, 29 females, mean age 57 years), and divided into a negative- (n = 17) and a positive post-therapeutic whole body scintigraphy group (n = 22). Pre- and post-therapeutic thyroglobulin course were analysed using non-linear regression, comparing the difference in the thyroglobulin growth coefficient b1 post- and pre-therapy (delta b1: b1(post-therapy)-b1(pre-therapy)). In addition, absolute post- and pre-therapeutic thyroglobulin levels, radiological follow-up and clinical outcome were also analysed. RESULTS: The two groups were comparable with respect to age, sex, tumour stage, histology and prior therapies. Differences between post- and pre-therapeutic b1 values differed significantly in the positive post-therapeutic whole body scintigraphy group (delta b1: -0.65 microg/l-1 years-1, P < 0.001) but not in the negative post-therapeutic whole body scintigraphy group (delta b1: -0.14). Absolute serum thyroglobulin levels and radiological follow-up revealed a favourable response of radioiodine therapy in the positive whole body scintigraphy group but not in the negative group. Delta b1 was related significantly with clinical outcome as revealed by receiver operator curves (ROC): all patients with a positive delta b1 (n = 8) had an unfavourable outcome (progression or death), whereas from the 31 patients with negative delta b1, 61% had an unfavourable outcome. CONCLUSION: We did not find disadvantageous effects of a single radioiodine therapy on serum thyroglobulin increments in patients with negative post-therapeutic whole body scintigraphy. However, as we did not observe a beneficial effect either, we would not advise the continuation of radioiodine therapy in patients with negative post-therapeutic whole-body scintigraphy, unless a positive response is observed in individual cases.