Twenty-two patients with spontaneously occurring primary hypothyroidism were studied to evaluate the spontaneous reversibility of the hypothyroid state. Twelve (54.5%) became euthyroid after restriction of iodine intake for 3 weeks (reversible type). In the remaining 10 patients, thyroid function did not improve with restriction of iodine alone, and thus, replacement therapy was required, (irreversible type). In the reversible type, 1) radioactive iodine uptake after 1 week of restricted iodine intake was higher than in the irreversible type [50.0 +/- 12.2% (+/- SD) vs. 4.3 +/- 3.2%; P less than 0.01], 2) the perchlorate discharge test was positive in 2 of 10 patients, and 3) the iodine-perchlorate discharge test, carried out in 7 of 8 patients with negative perchlorate discharge test, was positive in 6. Seven patients with the reversible type were given 25 mg iodine daily for 2-4 weeks; all became hypothyroid again. Two patients had a history of habitual ingestion of seaweed (25.4 and 43.1 mg iodine, respectively), but the remaining 10 patients ingested ordinary amounts of iodine (1-5 mg) daily. The patients with reversible hypothyroidism had focal lymphocytic thyroiditis changes in the thyroid biopsy specimen, whereas those with irreversible hypothyroidism had more severe destruction of the thyroid gland. These results indicate the existence of a reversible type of hypothyroidism sensitive to iodine restriction and characterized by relatively minor changes in lymphocytic thyroiditis histologically. Attention should be directed to this type of hypothyroidism, because thyroid function may revert to normal with iodine restriction alone.

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The effects of low and high NaCl diets on plasma glucose and insulin responses to glucose ingestion were investigated in 15 patients with essential hypertension. Oral glucose (75 g) tolerance tests were carried out while patients were taking diets with low (2 g/day) and high (20 g/day) NaCl content. Fasting plasma glucose and insulin levels were both significantly lower during ingestion of the high NaCl diet (p less than 0.05). After glucose ingestion, the incremental areas under the two hour plasma glucose and insulin curves were significantly smaller during ingestion of the high NaCl diet (glucose p less than 0.005 and insulin p less than 0.025). These findings that low NaCl diets increase the glycemic response to glucose loads suggest that use of NaCl restriction for the treatment of essential hypertension may not always be desirable.

SUMMARYIn order to investigate the validity of angiotensin converting enzyme inhibition with captopril as a screening test for primary aldosteronism (PA), 50mg of captopril were administered orally to 7 patients with PA, 17 with essential hypertension (EH), 5 with renovascular hypertension (RVH), 2 with renoparenchymal hypertension (RH) and 8 normal volunteers.The plasma aldosterone concentration (PAC) was suppressed to less than 15ng/dl in all of the EH, RVH and RH patients and normal subjects 90 min after administration of captopril, but not suppressed in 6 of 7 patients with PA. In addition, the plasma renin activity (PRA) was increased to greater than 1ng/ml/h in 10 of 17 patients with EH and in all with RVH, RH and the normal controls, but to less than that in 6 of 7 PA and the remaining EH patients. The PAC to PRA ratio after captopril was greater than 20 in all patients with PA, while it remained below 20 in EH, RVH and RH patients and normal controls.From these results, we conclude that the PAC to PRA ratio in the captopril administration test is a simple and useful tool to detect PA in hypertensive patients. In addition, the test has a great advantage in that it can be safely applied to outpatients with relatively severe hypertension. Additional Indexing Words: Primary aldosteronismAldosterone to renin ratio Captopril

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To find the best timing for administration of long-acting antihypertensive drugs, we gave nitrendipine, a calcium antagonist of the dihydropyridine group, once a day to six hospitalized and drug-free patients with essential hypertension, changing the time of administration and studying the effects on the circadian rhythm of blood pressure. After control values of 24-hour blood pressure variations were taken with patients on placebo, a 10-mg tablet of nitrendipine was given for 3 days on three occasions -at 6 AM on awakening, at 8:30 AM after breakfast, and at 6 PM after supper; 24-hour blood pressure values for each period were recorded on the third day. The 24-hour blood pressure values during the control period showed a biphasic circadian rhythm, with higher values during wakefulness and lower values during sleep. The control period was also characterized by a rapid rise in blood pressure on awakening, the so-called morning surge of blood pressure, and a gradual decline during sleep at night. Although the morning surge was not completely suppressed by nitrendipine given after breakfast, it was diminished by the drug given on awakening or after supper, the latter brought a deeper decline in blood pressure during sleep compared with other times. The average of 24-hour blood pressure values obtained by nitrendipine given on awakening was the lowest among the three occasions. Thus, administration of long-acting calcium antagonists with a rapid onset of action on awakening in the early morning seems to be a more rational and beneficial alternative than the conventional administration after breakfast. The earlier administration may prevent dangerous cardiovascular catastrophes, including stroke, myocardial infarction, and sudden death, known to occur often during the morning surge of blood pressure. 91214 have been shown to increase between the hours of 6 and 9 AM compared with the rest of the day. A number of precipitating factors may be involved in these early morning catastrophes, but the marked rise in blood pressure almost certainly is a major factor, perhaps by causing a rupture of atherosclerotic plaques whereby thrombus is formed. 9 Antihypertensive drugs that are given once a day have come into common use in the treatment of essential hypertension. Nitrendipine is one of the long-acting calcium antagonists of the dihydropyridine group whose clinical usefulness in the treatment of essential hypertension has been established either as monotherapy 1517 or in combination with /J-blockers. 18 Nitrendipine has a rapid onset of action and is usually given once or twice From the Department of Internal Medicine III, Kumamoto (Japan) University Medical School.Correspondence to Teruhisa Umeda, MD, Department of Internal Medicine III, Kumamoto University Medical School, 1-1-1 Honjo, Kumamoto 860, Japan. a day. Pharmacokinetic studies on dihydropyridine calcium antagonists performed in hypertensive patients 19 ' 20 have also found a relatively straight correlation between the logarithmic value of the pla...

This study investigated whether the change of glycemic response to oral glucose loading with an increase of dietary NaCl intake is different between salt-sensitive and salt-resistant groups, or whether it is related to glucose tolerance on a low NaCl diet independent of salt sensitivity. The plasma glucose and insulin response to 75 g oral glucose intake was assessed on low (34 mmol/day) and high (342 mmol/day) NaCl diets in 31 patients with essential hypertension, and the area under the curve for both variables (AUCglu and AUCins) was calculated. The data on the high NaCl diet were corrected for change in hematocrit. The percentage change in systolic, diastolic, and mean blood pressure between the two diets was defined as the salt sensitivity index (SSI) for systolic blood pressure (SSISBP), diastolic blood pressure (SSIDBP), and mean blood pressure (SSIMBP), respectively. The mean values of both AUCglu and AUCins decreased significantly with increase of NaCl intake; however, there was no significant correlation between SSI (SSISBP, SSIDBP, or SSIMBP) and the percentage changes in AUCglu and AUCins. Meanwhile, the percentage changes in AUCglu and AUCins significantly correlated with the respective values of AUCglu and AUCins on the low NaCl diet. These results suggest that extreme NaCl restriction may deteriorate glucose metabolism in hypertensive patients, especially in those with diabetes mellitus or impaired glucose tolerance.

The case of a 60-year