Impairment in cognitive and exercise performance during prolonged antarctic residence: effect of thyroxine supplementation in the polar triiodothyronine syndrome.

Humans who work in Antarctica display deficits in cognition, disturbances in mood, increased energy requirements, a decline of thyroid hormone products, and an increase of serum TSH. We compared measurements in 12 subjects, before deployment (baseline), with 11 monthly studies during Antarctic residence (AR). After 4 months of AR (period 1), half of the subjects (T(4) group) received L-thyroxine [64 nmol.day(-)(1) (0.05 mg.day(-)(1))]; and the other half, a placebo (placebo group) for the next 7 months of AR (period 2). During period 1, there was a 12.3 +/- 5.1% (P < 0.03) decline on the matching-to-sample (M-t-S) cognitive task and an increase in depressive symptoms, compared with baseline. During the intervention in period 2, M-t-S scores for the T(4)-treated group returned to baseline values; whereas the placebo group, in contrast, showed a reduced M-t-S score (11.2 +/- 1.3%; P < 0.0003) and serum free T(4) (5.9 +/- 2.4%; P < 0.02), compared with baseline. The change in M-t-S score was correlated with the change in free T(4) (P < 0.0003) during both periods, and increases in serum TSH preceded worsening scores in depression, tension, anger, lack of vigor, and total mood disturbance (P < 0.001) during period 2. Additionally, the submaximal work rate for a fixed O(2) use decreased 22.5 +/- 4.9% in period 1 and remained below baseline in period 2 (25.2 +/- 2.3%; P < 0.005) for both groups. After 4 months of AR, the L-thyroxine supplement was associated with improved cognition, which seems related to circulating T(4). Submaximal exercise performance decrements, observed during AR, were not changed with this L-thyroxine dose.

Secondary hyperparathyroidism following biliopancreatic diversion.

OBJECTIVE: To investigate the cause of osteomalacia following biliopancreatic diversion(BPD) surgery for obesity. DESIGN: A retrospective, case-comparison study. SETTING: A tertiary care center. PATIENTS: A case group of 12 subjects (including 9 women; mean age +/- SEM, 48.5 +/- 3.0 years; mean preoperative body mass index +/- SEM, 43.7 +/- 2.3 kg/m2, and mean weight loss +/- SEM, 75 +/- 14 kg) who have undergone BPD (referred to as BPD group hereafter) and a comparison group of 10 subjects (including 9 women; mean age +/- SEM, 49.6 +/- 3.3 years; mean preoperative body mass index +/- SEM, 44.0 +/- 2.5 kg/m2; and mean weight loss +/- SEM, 55 +/- 15 kg) following vertical banded gastroplasty (VBG) (referred to as VBG group hereafter). MAIN OUTCOME MEASURES: Serum and urine markers for bone metabolism. RESULTS: Compared with the VBG group, the BPD group had significantly lower concentrations of the following components: serum calcium (2.14 +/- 0.05 mmol/L vs 2.37 +/- 0.05 mmol/L [8.6 +/- 0.2 mg/dL vs 9.5 +/- 0.2 mg/dL]), serum 25-hydroxyvitamin D (24 +/- 6 nmol/L vs 64 +/- 6 nmol/L), urine calcium excretion (1.7 +/- 0.7 mmol/d vs 4.5 +/- 0.7 mmol/d [68 +/- 28 mg/d vs 180 +/- 28 mg/d]), and serum carotene (0.40 +/- 0.15 mmol/L vs 1.29 +/- 0.16 mmol/L). The BPD group had significantly higher concentrations of the following components: serum parathyroid hormone (13.6 +/- 2.1 pmol/L vs 5.2 +/- 2.3 pmol/L), serum alkaline phosphatase (139 +/- 8 U/L vs 86 +/- 9 U/L), and urinary hydroxyproline/creatine (52 +/- 5 mumol/mmol vs 19 +/- 5 mumol/mmol). CONCLUSION: These data suggest that following BPD, secondary hyperparathyroidism attributed to hypocalcemia results from malabsorption of vitamin D. However, we cannot exclude the possibility of concurrent calcium malabsorption with vitamin D malabsorption.

Thyroid adaptation to chronic tetraglycine hydroperiodide water purification tablet use.

Tetraglycine hydroperiodide tablets purify water by liberating 8 mg free iodine/tablet. The effects of ingesting four tablets daily for 3 months on thyroid size, function, and radioactive iodine uptake were studied prospectively in eight healthy volunteers. Serum inorganic iodide increased from 2.7 to approximately 100 micrograms/dL. Urinary iodide excretion rose 150-fold from a pretreatment mean of 0.276 to 40 mg/day. Radioactive iodine uptake was less than 2% after 7 days and remained below 2% in all subjects at 90 days. Mean serum T4 and T3 declined after 7 days. T4 remained below baseline, whereas T3 had recovered by the end of the treatment period. Serum TSH and the TSH response to TRH rose significantly after 7 days and remained elevated at 3 months. The average thyroid volume, determined by ultrasound, increased by 37%. Neither hyperthyroidism nor hypothyroidism was observed. The mean thyroid volume in seven subjects available for repeat determinations an average of 7.1 months after the study was not different from the baseline value. In normal subjects, a reversible TSH-dependent thyroid enlargement occurs in response to the iodine load from daily use of tetraglycine hydroperiodide water purification tablets.

Symptomatic Chiari-I malformation in a patient with acromegaly.

We describe, for the first time, a patient with both symptomatic acromegaly and Chiari-I malformation. These conditions could coexist by chance alone, but the probability of both presenting simultaneously in a previously healthy man seem quite remote. Alternatively, acromegaly through associated bony and soft tissue enlargement could lead to the development of symptoms from Chiari-I malformation in this patient.

Effect of cold remedies on metabolic control of NIDDM.

OBJECTIVE: To compare the effects of two cough syrup formulations (one with sugar and alcohol and one without) on the metabolic control of NIDDM. RESEARCH DESIGN AND METHODS: A prospective, blinded cross-over study was performed at the Endocrinology Clinic of a U.S. Army Medical Center on 20 volunteers with NIDDM, treated with diet alone or diet plus an oral hypoglycemic agent. After a 7-day lead-in period, patients took 3-day courses of each cough syrup (10 ml 4 times/day) with an intervening 4-day wash-out period. Fasting and postprandial blood glucose and lipids before and immediately after each course were compared. RESULTS: No differences in pretherapy and posttherapy values were found with either formula. Values taken after the sugar- and alcohol-containing formula were not different from those taken after the alcohol- and sugar-free formula. CONCLUSIONS: We conclude that patients with NIDDM can take standard daytime cough formulas, in short courses of standard doses, without adverse effect on blood glucose or lipids.

Covert hypothyroidism presenting as a cardiovascular event.

Hypothyroidism presenting with classic signs and symptoms is generally easily recognized. Less often, patients with hypothyroidism may present with symptoms and laboratory abnormalities suggestive of cardiovascular disease. In this article, we describe six such patients. Hypothyroidism was suspected when creatine phosphokinase (CPK) levels were persistently elevated. The diagnosis was confirmed by thyroid function tests, and thyroid hormone therapy resulted in resolution of symptoms and CPK elevations. Persistently elevated CPK levels associated with cardiovascular symptoms but without demonstrable myocardial damage should prompt consideration of covert hypothyroidism.

Does screening proctosigmoidoscopy result in reduced mortality from colorectal cancer? A critical review of the literature.

OBJECTIVE: To determine the strength of the evidence in the literature that screening proctosigmoidoscopy reduces colorectal cancer mortality. DESIGN: All English-language studies reporting mortality or survival from screening proctosigmoidoscopy published since 1960 were critically reviewed. DATA EXTRACTION: Fifteen references reported on five studies of screening proctosigmoidoscopy. Two authors independently reviewed each reference using explicit methodologic criteria, particularly for potential sources of bias. MEASUREMENTS AND MAIN RESULTS: Of the five studies, four used historical controls and were susceptible to bias, especially self-selection and lead-time bias. Only the Kaiser-Permanente Multiphasic Health Check-up study collected a representative patient sample from a defined population, had randomly allocated controls, and avoided multiple sources of bias. There was a reduction in mortality from a group of seven potentially postponable causes of mortality, including colorectal cancer, although no difference in overall mortality between screened and control groups was found. This study was not designed to determine specifically the impact of screening proctosigmoidoscopy on mortality from colorectal cancer, and suggested that most of the reduction in colorectal cancer deaths was due to a lower incidence in the screened group, which could not be attributed to polypectomy. The benefit of screening proctosigmoidoscopy in this study, if any, was small. CONCLUSIONS: The evidence in the literature is inadequate to determine whether or not screening proctosigmoidoscopy has an impact on colorectal cancer mortality, but the best available data suggest that the benefit is small, at best.