as 10% of the filtered load, although fractional Na+ excretions of 5% are more common. At usual clinical doses, however, the thiazide diuretics generally increase excretion of Na+ and Cl", with an accompanying loss of K+. Thus, unlike that of the carbonic anhydrase inhibitors, the diuresis produced by thiazide and thiazide-like diuretics is of NaCl and not NaHCO3. The urinary K+ wasting induced by the thiazides is primarily a consequence of the increased Na+ delivered to the distal tubule as discussed earlier.
Two renal responses are unique to the thiazide and thiazidelike diuretics. With these compounds, Na+ excretion is increased, while Ca++ excretion is decreased, primarily and directly because of increased distal Ca++ reabsorption, secondarily and indirectly because of a compensatory elevation of proximal solute absorption, making this class of diuretics useful in treating hypercal-ciuria. This effect, which may not be evident upon initial administration of the drug, is particularly beneficial in individuals who are prone to calcium stone formation.
A second unusual action of this class of diuretics is their utility in treating nephrogenic diabetes insipidus. Patients who have an adequate supply of ADH but whose kidneys fail to respond to ADH excrete large volumes of very dilute urine, not unlike those who have an ADH deficiency. The thiazides reduce glomerular filtration modestly and decrease positive free water formation (CHO), that is, production of dilute urine. These actions combine to cause patients with nephrogenic diabetes insipidus to excrete a somewhat reduced urine volume with increased osmolality.
Was this article helpful?
All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.