Cases reported "Hyperkalemia"

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1/16. Familial pseudohyperkalemia maps to the same locus as dehydrated hereditary stomatocytosis (hereditary xerocytosis).

    Familial pseudohyperkalemia is a "leaky red blood cell" condition in which the cells show a temperature-dependent loss of potassium (K) from red blood cells when stored at room temperature, manifesting as apparent hyperkalemia. The red blood cells show a reduced lifespan in vivo but there is no frank hemolysis. Studies of cation content and transport show a marginal increase in permeability at 37 degrees C and a degree of cellular dehydration, qualitatively similar to the changes seen in dehydrated hereditary stomatocytosis (hereditary xerocytosis). Physiological studies have shown that the passive leak to K has an abnormal temperature dependence, such that the leak is less sensitive to temperature than that in normal cells. We performed genetic mapping on the original family and found that the condition in this kindred maps to the same locus (16q23-ter) that we have previously identified for an Irish family with dehydrated hereditary stomatocytosis, which does not show the same temperature effects.
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2/16. Gordon's syndrome: increased maximal rate of the Na-K-Cl cotransport and erythrocyte membrane replacement of sphingomyelin by phosphatidylethanolamine.

    OBJECTIVE: Gordon's syndrome comprises hypertension, hyperchloremic acidemia, hyperkalemia and intact renal function. We hypothesize that disturbances of one or more cell membrane ion carriers, handling sodium, chloride and potassium, might be relevant in this disorder and, furthermore, that such disturbances might be related to altered.cell membrane composition. DESIGN AND methods: In a patient diagnosed with Gordon's syndrome, we assessed the kinetics (K(m) and maximal rate) of four membrane sodium transport systems in sodium-enriched erythrocytes, according to the technique of Garay. We also measured the lipid composition of erythrocyte membrane in this patient and 69 essential hypertensive controls, using the latroscan technique. RESULTS: Compared to reference values of patients with essential hypertension, this patient exhibited a marked increase in the maximal rate of the Na -K -2Cl(-)-cotransport (964.0 micromol/l per cell versus the 391.6 /- 222 micromol/l per cell in essential hypertensives). Also, there was an increased concentration of erythrocyte membrane phosphatidylethanolamine and a reduced concentration of sphingomyelin (27.9 and 11.1% versus 17.9 /- 3.8% and 18.2 /- 3.4%, respectively). CONCLUSIONS: We conclude that this abnormality in membrane Na -K -2Cl- cotransport could be responsible for the hyperkalemia, hyperchloremic acidemia and increased reabsorption of sodium observed in this condition and, furthermore, that such disturbance in membrane cotransport might be related to altered phospholipid concentration in cell membranes.
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3/16. Resolution of hypertension during pregnancy in familial hyperkalemia and hypertension with the WNK4 Q565E mutation.

    OBJECTIVE: Secondary hypertension during pregnancy usually carries high maternal and fetal morbidity and mortality rates. A rare form of monogenic hypertension is familial hyperkalemia and hypertension, which is caused by mutations in the kinases WNK1 or WNK4 and other unknown molecular defects. The purpose of the study was to examine the course of pregnancy in hypertensive women with familial hyperkalemia and hypertension. STUDY DESIGN: We prospectively studied 2 pregnancies of a woman with familial hyperkalemia and hypertension and the Q565E WNK4 mutation (pregnancies 1 and 2) and retrospectively studied the course of 2 pregnancies in another woman who was an affected member of this largest family described in the literature. RESULTS: Both women had hypertension (170-190/105-110 mm Hg), hyperkalemia (5.3-6.0 mmol/L), and hypercalciuria, all of which were well controlled by thiazides. During pregnancies, thiazides were discontinued; throughout the pregnancy, the blood pressure remained normal at 120 to 130/75 to 85 mm Hg; however, hyperkalemia and hypercalciuria, which were documented in pregnancies 1 and 2, persisted. renin and aldosterone levels (which were measured in pregnancies 1 and 2) rose towards their end. Four normal infants were born. A woman with familial hyperkalemia and hypertension of unknown molecular defect who had 2 pregnancies with hypertension exacerbation and premature deliveries was described previously. CONCLUSION: In familial hyperkalemia and hypertension with the WNK4 mutation, pregnancy ameliorates hypertension; however, hyperkalemia and hypercalciuria persist. This dissociation may shed light on the pathogenesis of familial hyperkalemia and hypertension, on pregnancy-related hypertension, and on the mechanism of action of WNK4 kinase, a major regulator of cellular ion transport.
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4/16. A new kindred with pseudohypoaldosteronism type II and a novel mutation (564D>H) in the acidic motif of the WNK4 gene.

    We identified a new kindred with the familial syndrome of hypertension and hyperkalemia (pseudohypoaldosteronism type II or Gordon's syndrome) containing an affected father and son. mutation analysis confirmed a single heterozygous G to C substitution within exon 7 (1690G>C) that causes a missense mutation within the acidic motif of WNK4 (564D>H). We confirmed the function of this novel mutation by coexpressing it in xenopus oocytes with either the NaCl cotransporter (NCCT) or the inwardly rectifying K-channel (ROMK). Wild-type WNK4 inhibits 22Na flux in xenopus oocytes expressing NCCT by approximately 90% (P<0.001), whereas the 564D>H mutant had no significantly inhibitory effect on flux through NCCT. In oocytes expressing ROMK, wild-type WNK4 produced >50% inhibition of steady-state current through ROMK at a 20-mV holding potential (P<0.001). The 564D>H mutant produced further inhibition with steady-state currents to some 60% to 70% of those seen with the wild-type WNK4. Using fluorescent-tagged NCCT (enhanced cyan fluorescent protein-NCCT) and ROMK (enhanced green fluorescent protein-ROMK) to quantify the expression of the proteins in the oocyte membrane, it appears that the functional effects of the 564D>H mutation can be explained by alteration in the surface expression of NCCT and ROMK. Compared with wild-type WNK4, WNK4 564D>H causes increased cell surface expression of NCCT but reduced expression of ROMK. This work confirms that the novel missense mutation in WNK4, 564D>H, is functionally active and highlights further how switching charge on a single residue in the acid motif of WNK4 affects its interaction with the thiazide-sensitive target NCCT and the potassium channel ROMK.
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5/16. Pseudohyperkalemia due to pneumatic tube transport in a leukemic patient.

    Pseudohyperkalemia is an elevation in measured serum or plasma potassium levels caused by mechanical release of potassium from cells during phlebotomy or specimen processing. We describe a case of pseudohyperkalemia caused by mechanical disruption of white blood cells from a leukemic patient because of pneumatic tube transport of the specimen. This is the first description of pneumatic tube transport causing pseudohyperkalemia, and clinicians should be aware of this potential cause of false elevation of plasma potassium levels.
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6/16. A patient with hyperkalemia and metabolic acidosis.

    Uptake of potassium by extrarenal tissues, primarily muscle and liver, represents a major defense mechanism in the maintenance of normokalemia following an acute elevation in the serum potassium concentration. insulin, epinephrine, and aldosterone all play major roles in maintaining the normal distribution of potassium between the intracellular and extracellular environment. In addition to hormonal regulation, changes in blood pH and tonicity also exert a strong influence on extrarenal potassium metabolism. Last, the serum potassium concentration per se directly influences its own cellular uptake and this transport mechanism appears to be inhibited by uremia.
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7/16. Nonazotemic hyperkalemia with renal and extrarenal defects in potassium transport: association with high levels of digoxin-like immunoreactive factor.

    We report a hypertensive patient with nonazotemic hyperkalemia caused by a combined disturbance in both the internal and external balance of potassium. During a follow-up of 30 months, exacerbations of hyperkalemia were observed, interposed with a return to the previous baseline. Two brief normokalemic periods were recorded. blood pressure tended to be higher during hyperkalemic peaks. The following findings were detected: (1) hyperchloremic hyperkalemic acidosis with normal glomerular filtration rate, adequately elevated plasma aldosterone levels, and normovolemia; (2) a tubular defect in potassium excretion, refractory to intravenous sodium sulfate (nonreabsorbable anion) and mineralocorticoids; (3) impaired tissue uptake of potassium under insulin administration; (4) exaggerated hyperkalemia following beta-adrenergic blockade and blunted hypokalemic response to a beta-agonist; and (5) a defect in Na/K transport in erythrocytes detected in vitro, coexistent with an elevated level of free digoxin-like immunoreactive factor in serum. These results suggest that our patient had a generalized abnormality in potassium transport.
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8/16. beta-Adrenergic treatment of hyperkalemic periodic paralysis.

    In a patient with hyperkalemic periodic paralysis, metaproterenol prevented muscular weakness and hyperkalemia in periods of rest after exercise. During a severe attack, the drug rapidly corrected hyperkalemia and seemed to enhance the return of strength. The action of metaproterenol may involve a beta-adrenergic-mediated increase of potassium transport via the sodium-potassium pump.
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9/16. crush syndrome.

    The crush syndrome has been an accompaniment of crushing injuries following disaster situations. Recognition of the sequence of events and early institution of the appropriate therapy is essential, if life is to be saved in these critically injured persons. Treatment should be begun 'on site' and arrangement then made for transport to a major medical facility as rapidly as feasible.
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10/16. Familial hyperkalemic periodic paralysis and bipolar disorder: a linkage and treatment study.

    Familial hyperkalemic periodic paralysis and bipolar disorder are both hereditary disorders, characterized by episodes of illness separated by periods of remission, and possibly related to abnormalities in cellular ion transport. Recently we discovered a patient who suffered from both illnesses, as did his mother and grandmother. However, a detailed investigation of the pedigree suggested that these two disorders are not linked genetically. Furthermore, a placebo-controlled double-blind trial of lithium carbonate in this patient found lithium ineffective in preventing the attacks of paralysis, in contrast to another recent study which found lithium effective in hypermagnesemic periodic paralysis.
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