In this study, the risk of iodine-induced thyrotoxicosis in unselected patients from an iodine-deficient area was investigated. The patients were consecutively enrolled. Thyroid hormone values and urinary iodine excretion were determined before, as well as 1, 4 and 12 weeks after iodine contamination by coronary angiography. Two of 788 unselected patients developed hyperthyroidism within 12 weeks. The two patients did not belong to a risk group for iodine-induced thyrotoxicosis (i.e. old people, patients with goiter or possible thyroid autonomy, low TSH). Both patients had normal TSH levels at baseline and ultrasound of the thyroid was without evidence of nodules. The study shows that in euthyroid unselected patients from an iodine-deficient area short-term iodine contamination by contrast media rarely leads to hyperthyroidism. On account of these facts, prophylactic therapy, e.g. by perchlorate or thiamazole, is not generally recommended, because the risk of side-effects is perhaps even greater than the risk of iodine-induced thyrotoxicosis.

Editor's Note: Talking about "blood pressure" as a single figure is similar to knowing the average height of a mountain range: an interesting statistic, but completely useless to a pilot trying to make it through a mountain pass alive. Realistically, we need to consider not merely the mean stress on an aging vascular endothelial cell, but the "peaks" that it has to "fly over" as well. Aging vessels are-to an extent-the end result of such stresses. Halberg et al. suggest that many patients may be apparently normotensive, yet (because of circadian peaks in blood pressure) have the catastrophic risks of any other severely hypertensive patient. They recommend that we avoid "flying blind" and begin to measure peak pressures more accurately if we are to avoid disaster. ABSTRACT Serial measurements, taken around the clock in the laboratory and clinic, can be analyzed by computer-implemented curve-fitting to assess the approximate 24-hour (circadian) variation, among other rhythmic and chaotic components of the time structure (chronome) of any vari¬ able. This approach is particularly important to quantify blood pressure variability, which renders even the most accurate single measurement into a snapshot on a roller coaster. A seemingly acceptable blood pressure can be particularly misleading when accompanied by the recommendation of another check-up in 2 years, which is the official position of the World Health Organization. An overswinging of the blood pressure along the 24-hour scale may then be missed. This excessive circadian amplitude, called "circadian hyper-amplitude-ten¬ sion" (CHAT), constitutes a new disease risk syndrome, warranting screening, diagnosis, and treatment. With or without the midline-estimating statistic of rhythm (MESOR) (i.e., the [chronome-adjusted] mean value), the circadian double amplitude, a measure of the extent of

Iodine plays an important role in thyroid physiology resulting from its importance as a requisite substrate for the synthesis of thyroid hormones and from its action as a regulator of thyroid function. Following intestinal absorption, inorganic iodide is largely confined to the extracellular fluid. Serum concentrations of inorganic iodide well reflect the amount of iodine present in the extracellular compartment. Since serum inorganic iodide levels are important determinants of thyroid iodine uptake, serum iodide measurement offers a valuable tool for the investigation of many basic and clinical aspects of thyroid iodine metabolism. Here we summarize important aspects of iodine metabolism and focus selectively on technical aspects of serum inorganic iodide measurement and on the kinetics of inorganic iodide in various states of iodine excess. Presently, paired-ion, reversed-phase HPLC with electrochemical detection is obviously the best method for measurement of serum inorganic iodide being highly sensitive, easy to perform, and almost completely insensitive to interfering substances. Using this method, we could demonstrate an acute increase of serum inorganic iodide during the administration of large amounts of iodide as Lugol's solution given preoperatively in patients with Graves' hyperthyroidism. In patients under treatment with the iodine containing drug amiodarone (n=37), serum inorganic iodide levels were highly elevated (range 3.5-208.2 microg/dl, median 36.6 microg/dl). Serum concentrations of inorganic iodide were correlated neither to the daily amiodarone dose, nor to the serum levels of amiodarone.

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