Potassium depletion

The major mineralocorticoid, aldosterone, is secreted by cells of the zona glomerulosa. Primary hyperaldosteronism (Conn s syndrome) is associated with potassium depletion which is, in mm, responsible for the observed neuromuscular abnormalities seen in the disorder. These are similar to those seen in hypokalemic periodic paralysis (PP), with episodic and severe exacerbations of fixed muscle weakness. Muscle biopsy shows occasional muscle necrosis and vacuoles often these feamres are accompanied by mbular aggregates as in hypokalemic PP. All these changes can be attributed to the hypokalemia and not to excess aldosterone production per se. 

Figure 7 Comparison of experimental and modeled potassium depletion in the soil close to a planar mat of rape roots for three soil levels. The modeled lines were calculated using the Barber-Cushman model. (From Ref. 104.)...

Perspiratory losses in patients with cystic fibrosis ° Mild-to-moderate potassium depletion (renal ammoniagenesis)... 

Whenever possible, potassium supplementation should be administered by mouth. Of the available salts, potassium chloride is most commonly used because it is the most effective for common causes of potassium depletion. 

Potassium depletion Low-pH shock treatment Methyl-P-cyclodextrin... 

For potassium depletion, cells are washed with potassium-free buffer (140 mM NaCl, 20 mM 4-(2-hydroxyethyl)-l-piperazineethanesulfonic acid (HEPES), ImM CaCh, Img/mL o-glucose, pH 7.4) and then rinsed in hypotonic buffer (potassium-free buffer 1 1 diluted with distilled water) for five minutes. Then, cells are quickly washed three times in potassium-free buffer followed by incubation for 20 minutes at 37°C in buffer. Control experiments are performed in the same manner, except all solutions additionally contain 10 mM KCl. 

Prevention of potassium depletion when dietary intake is inadequate in the following conditions Patients receiving digitalis and diuretics for CHF significant cardiac arrhythmias hepatic cirrhosis with ascites states of aldosterone excess with normal renal function potassium-losing nephropathy certain diarrheal states. 

Individualize dosage. Usual range is 16 to 24 mEq/day for the prevention of hypokalemia to 40 to 100 mEq/day or more for the treatment of potassium depletion. 

Pharmacokinetics Normally about 80% to 90% of potassium intake is excreted in urine with the remainder voided in stool and, to a small extent, in perspiration. Kidneys do not conserve potassium well during fasting or in patients on a potassium-free diet, potassium loss from the body continues, resulting in potassium depletion. A deficiency of either potassium or chloride will lead to a deficit of the other. 

Metabolic acidosis and hyperchioremia Potassium depletion is rarely associated with metabolic acidosis and hyperchloremia. Replace with potassium bicarbonate, citrate, acetate, or gluconate. 

Metabolic alkalosis Potassium depletion is usually accompanied by an obligatory loss of chloride resulting in hypochloremic metabolic alkalosis. Treat the underlying cause of potassium depletion and administer IV potassium chloride. 

Potassium depletion Potassium depletion may predispose to metabolic alkalosis. 

The degree of blockade can be influenced by body pH and electrolyte balance. Hypokalemia due to diarrhea, renal disease, or use of potassium-depleting diuretics potentiates the effect of nondepolarizing blockers. By contrast, hyperkalemia may oppose the actions of d-tubocurarine but enhance the end plate response to succinylcholine. The effectiveness of d-tubocurarine is reduced by alkalosis. 

Be especially alert for signs of potassium depletion, such as cardiac arrhythmias, in patients taking digoxin... 

The mercury ion is capable of causing local or systemic toxicity. For local irritation, they are combined with theophylline in an attempt to diminish the irritative toxicity at the site of injection. IV administration may lead to ventricular arrhythmias. They cause hepatocellular damage and even precipitate hepatic failure. They can also lead to low salt syndrome, hypochloraemic alkalosis and potassium depletion. 

Potassium-sparing diuretics are useful both to avoid excessive potassium depletion and to enhance the natriuretic effects of other diuretics. Aldosterone receptor antagonists in particular also have a favorable effect on cardiac function in people with heart failure. 

Potassium-depleting diuretics, except indapamide, can attenuate the effect of lovastatin on blood lipid concentrations (12). 

Aruna AS, Akula SK, Sarpong DF. Interaction between potassium-depleting diuretics and lovastatin in hypercholes-terolemic ambulatory care patients. J Pharm Technol 1997 13 21-6. 

Excessive retention of sodium ions in the body leads to increased release of antidiuretic hormone and a resulting increase in body water. Many diuretics such as chlorothiazide (i) and clopamide (2) inhibit sodium and chloride ion resorption in the kidney tubules and promote potassium depletion, whereas amiloride (J) and triamterene ( 4) diminish the excretion of potassium while causing a loss of sodium ions6. Other diuretics such as acetazolamide (5) and dichlorphenamide (6) inhibit the ion-exchange reaction catalysed by the zinc-containing enzyme carbonic an-hydrase. 

The most serious side effects of diuretics are fluid depletion and electrolyte imbalance.13,88 By the very nature of their action, diuretics decrease extracellular fluid volume as well as produce sodium depletion (hyponatremia) and potassium depletion (hypokalemia). Hypokalemia is a particular problem with the thiazide and loop diuretics, but occurs less frequently when the potassium-sparing agents are used. Hypokalemia and other disturbances in fluid and electrolyte balance can produce serious metabolic and cardiac problems and may even prove fatal in some individuals. Consequently, patients must be monitored closely, and the drug dosage should be maintained at the lowest effective dose. Also, potassium supplements are used in some patients to prevent hypokalemia. 

Other drugs may increase the effects of dextroamphetamine. For example, bicarbonate and other alkalin-izing agents increase the amount of amphetamines absorbed in the digestive system. Thiazides (potassium-depleting diuretics) decrease the amount of amphetamines that leave the body in urine. Also, other central nervous system stimulants, such as cocaine and nicotine, can amplify the stimulating effects of dextroamphetamines. 

Thiazide diuretics such as chlorothiazide (Diuril) and hydrochlorothiazide (HCTZ) work by blocking the action of aldosterone, a hormone that promotes sodium reabsorption by the kidneys. They are potassium-deplet-... 

The potassium-depleting diuretics (e.g., hydrochlorothiazide, chlorthalidone, metolazone) cause potassium loss that may be reversed by supplementation and/or dietary adjustments. As previously stated, potassium can be harmful in high amounts, so any supplementation should be recommended and supervised by a doctor. 

Drugs that are also known to decrease potassium levels, such as glucocorticoids and digoxin, should be avoided by anyone taking potassium-depleting diuretics. If they are prescribed, a physician should closely monitor the potassium levels of the patient. Potassium deficiency, or hypokalemia, can cause serious and potentially dangerous side effects (see Harmful side effects section). 

Hinsinger, P., and Jaillard, B. (1993). Root-induced release of interlayer potassium and ver-miculitization of phlogopite as related to potassium depletion in the rhizosphere of ryegrass. /. Soil Sci. 44,525-534. 

Sayles, F.L., Wilson, T.R., Hume, D.H. and Mangelsdorf, PC. (1973) In situ sampler for marine sedimentary pore waters evidence for potassium depletion and calcium enrichment. Science, 181, 154-156. 

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