Hyperkalemic

Mutations of the NaVl. 4 channel gene cause various types of muscle diseases, including hyperkalemic periodic paralysis, paramyotonia congenita, myotonia fluctuans, acetazolamide-sensitive myotonia. Mutations disiupt inactivation and cause both myotonia (enhanced excitability) and attacks of paralysis (inexcitability resulting from depolarization). 

Hyperkalemic periodic paralysis AD 17q13 Sodium channel alpha subunit... 

This is another group of diseases characterized by abnormalities in muscle fiber excitability. They are all periodic in the sense that periods of normal behavior are interspersed with periods of abnormally depressed excitability. During these latter phases, which may last for anything from a few hours to several days, there is a characteristic muscular weakness. The conditions are usually subdivided on the basis of serum levels during paralytic episodes, and are thus described as hyperkalemic, normokalemic, or hypokalemic. 

Primary hyperkalemic periodic paralysis is usually first manifest in childhood. Attacks may last for a period of a few hours to several days, and the degree of muscle damage associated with the condition appears to increase with age and frequency of attacks. Vacuolation and dilatation of the SR is the most obvious form of damage, and it increases with age. 

Hyperkalemic periodic paralysis (MIM 170500) Sodium channel Skeletal muscle... 

In patients with peritonitis, hypovolemia is often accompanied by acidosis, so large volumes of a solution such as lac-tated Ringers may be required initially to restore intravascular volume. Maintenance fluids should be instituted (after intravascular volume is restored) with 0.9% sodium chloride and potassium chloride (20 mEq/L) or 5% dextrose and 0.45% sodium chloride with potassium chloride (20 mEq/L). The administration rate should be based on estimated daily fluid loss through urine and nasogastric suction, including 0.5 to 1.0 L for insensible fluid loss. Potassium would not be included routinely if the patient is hyperkalemic or has renal insufficiency. Aggressive fluid therapy often must be continued in the postoperative period because fluid will continue to sequester in the peritoneal cavity, bowel wall, and lumen. 

Mutations of the sodium channel cause hyperkalemic periodic paralysis and paramyotonia congenital 720... 

Hyperkalemic ECG disturbances of cardiac function Adi]ust dosage by constant monitoring of ECG changes during administration. 

I.c.2.3. Hyperkalemia. Treatment of hyperkalemia depends on the level of the serum potassium, the state of neuromuscular irritability and the chronicity of the hyperkalemic state. In acute hyper-kalemic states, if the serum potassium is less than... 

Blood pressure, edema, urine output, urine electrolytes, BUN, creatinine, ECG (if hyperkalemic), gynecomasfia, impotence, weight... 

Amiloride Blocks epithelial sodium channels in collecting tubules Reduces Na retention and wasting increases lithium clearance Hypokalemia from other diuretics reduces lithium-induced polyuria Orally active duration 24 h Toxicity Hyperkalemic metabolic acidosis... 

Potassium supplements [P] Additive hyperkalemic effect especially a problem in presence of renal impairment. 

TThe importance of ion channels to physiological processes is clear from the effects of mutations in specific ion-channel proteins (Table 11-8). Genetic defects in the voltage-gated Na+ channel of the myocyte plasma membrane result in diseases in which muscles are periodically either paralyzed (as in hyperkalemic pe-... 

Heparin-induced hypoaldosteronism is well documented, both in patients treated with standard heparin, even at low doses, and in patients treated with low molecular weight heparin (477,478). The most important mechanism of aldosterone inhibition appears to be a reduction in both the number and affinity of angiotensin II receptors in the zona glomerulosa (477). A direct effect of heparin on aldosterone synthesis, with inhibition of conversion of corticosterone to 18-hydroxycorticosterone, has also been suggested. This effect is believed to be responsible for the hyperkalemia that can occur in heparin-treated patients with impaired renal function and particularly in patients on chronic hemodialysis (479), or with diabetes mellitus, or who are taking other potentially hyperkalemic drugs. 

Treatment with potassium and magnesium may be indicated. Potassium is recommended for patients with digitalis-induced ectopic beat or tachycardia, provided the patient is not hyperkalemic, uremic, or oliguric. It is the preferred drug if the patient is hypokalemic. 

Potassium-sparing diuretics (amiloride, spironolactone, triamterene) Additive effects with other agents increasing serum potassium concentration. May alter renal excretion of substances other than potassium (eg, digoxin, hydrogen ions). ACE inhibitors [NE] Additive hyperkalemic effect. 

Calcium-channel blockers are used for treating cardiac arrhythmia and pulmonary hypertension and for prevention of reperfusion injury. Sodium channels have been linked to epilepsy and hyperkalemic periodic paralysis (Table 8.1). 

SCN4A 17q23.1-25.3 Navi.4 Hyperkalemic periodic paralysis PC PAM D Gain... 

Mitrovic N, George AL Jr, Lerche H, Wagner S, Fahlke C, Lehmann-Horn F. Different effects on gating of three myotonia-causing mutations in the inactivation gate of the human muscle sodium channel. J Physiol. 1995 Aug 15 487 (Pt 1) 107-114. Lehmann-Horn F, laizzo PA, Halt H, Franke C. Altered gating and conductance of Na+ channels in hyperkalemic periodic paralysis. Pfliig. Arch. Fur. J. Phy. 1991 418 297-299. 

Cannon SC, Brown RH Jr, Corey DP. A sodium channel defect in hyperkalemic periodic paralysis potassium-induced failure of inactivation. Neuron 1991 6 619-626. 

NSAIDs can cause hyperkalemic acidosis and should be used with caution in the presence of renal impairment (4). 

Hyperkalemic muscle paralysis has been reported in renal insufficiency and trauma and in patients taking spironolactone and amUoride plus hydrochlorothiazide (co-amilozide). ACE inhibitors inhibit the release of aldosterone, reducing renal potassium loss, which can be enhanced by potassiumsparing diuretics or pre-existing renal insufficiency. 

Patients with end-stage renal disease on dialysis can have an enhanced hyperkalemic response to labetalol, which is partly attributable to electrochemical disturbances in the cells, characterized by an increase in intracellular sodium and chloride and a fall in intracellular potassium. 

A 47-year-old woman had an infusion of propofol 200 micrograms/kg/minute for 4 days. On day 2 she developed hematuria, and laboratory investigations showed renal insufficiency with hyperkalemic metabolic acidosis. She died as a result of rhabdomyolysis with cardiac involvement. 

Rado JP, Marosi J, Szende L, Tako J. Hyperkalemic changes during spironolactone therapy for cirrhosis and ascites, with special reference to hyperkalemic intermittent paralysis. J Am Geriatr Soc 1968 16(8) 874-86. 

There is an association between (latent) muscular dystrophy (usually of the Duchenne or Becker type) and the production of rhabdomyolysis by suxamethonium (84,85,89,90). Suxamethonium can cause excessive muscle damage in these patients, as manifested not only by severe myoglobinemia and raised serum creatine kinase activity but also by acute exacerbation of muscle weakness postoperatively (SEDA-11, 121) (7,29,84,91,92). Massive potassium release can result in hyperkalemic cardiac arrest. Such patients may also develop features suggestive of the syndrome of malignant hyperthermia (93,94). Suxamethonium should not be used in patients with Duchenne muscular dystrophy or who have a family history suspect for the condition. 

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