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Endocrinology

Hyperpotassemia and hypopotassemia

Table of contents
Hyperpotassemia and hypopotassemia
Anamnesis of a hyperpotassemia
Diagnostic approach at a hyperpotassemia
Renal canalicular acidosis with a hyperpotassemia and a hypopotassemia
Hypopotassemia
Diagnostic approach at a hypopotassemia

The hyperpotassemia on MKB-10 belongs to the class:
Diseases of endocrine system, disorder of food and disbolism
Block:
Disbolism
Code:
E87.5

The hyperpotassemia is characterized by increase of potassium concentration in blood serum from 5,5 mmol/l and more.

POTASSIUM METABOLISM

Regulation of balance of potassium has paramount importance in maintenance of a homeostasis. At rather little changes of potassium concentration in extracellular space considerable incidence and mortality can be noted. In regulation of balance of potassium the large role is played by kidneys. In normal conditions of people consumes with food 60 — 100 mmol of potassium in days; from this number from 5 to 10 mmol less than 5 mmol when sweating are allocated with a stake, and the rest with urine.

The general reserves of potassium in an organism make about 40 — 45 mmol/kg of body weight. From this number of 90% of potassium is in intracellular space and easily enters an exchange from 2%, being in extracellular liquid spaces; other 8% of potassium are in a bone tissue and do not take part in fast exchange processes. Normal potassium concentration in extracellular liquid fluctuates from 3,6 to 5 mmol/l. Intracellular concentration of this ion makes from 140 to 160 mmol/l. In spite of the fact that there is a correlation communication between potassium concentration in extracellular liquid and the general content of potassium in an organism, this dependence is very approximate, and sometimes very insignificant. Happens that major deficit of the general content of potassium in an organism is combined with normal potassium concentration in extracellular liquid. In exceptional clinical cases the content of potassium in plasma can serve as an indicator of the general reserves of potassium in an organism.

Regulation of an exchange of potassium of kidneys

For simplicity it is possible to consider that practically all potassium is exposed to filtering in kidneys. Therefore, potassium concentration in a glomerular filtrate will precisely correspond to its concentration in plasma. About 50% of the filtered potassium reabsorbirutsya in proximal tubules, 40% reabsorbirutsya in the ascending Henle's loop knee. The further reabsorption of potassium occurs in distal tubules and collective tubules. Nevertheless the most part of potassium of urine is provided cosecreted in distal tubules and collective tubules. The collective tubule is the final regulator of secretion of potassium. The knowledge of the factors influencing secretion of potassium in this segment of nephron and its excretion is important very much.

The factors influencing secretion of potassium in distal departments of nephron

Possibly, the only most important factor influencing potassium secretion level is the amount of the sodium delivered in a collective tubule. The absolute amount of the sodium reaching a collective tubule decreases in cases of reduction of an effective arterial blood-groove (at the same time there is a decrease in level of glomerular filtering and increase of level of a reabsorption in proximal departments of nephron). Therefore, reduction of amount of the sodium capable to exchange on potassium leads to potassium secretion reduction. The second important regulator of level of secretion of potassium in collective tubules is Aldosteronum. At the constant level of intake of electrolytes in distal departments of nephron Aldosteronum accelerates a sodium exchange for potassium while for lack of Aldosteronum irrespective of increase or reduction of amount of the sodium delivered in collective tubules this process is slowed down; therefore, Aldosteronum possesses an important role in potassium secretion regulation.

Sodium can reabsorbirovatsya in the form of chloride sodium. If delivery of sodium in collective tubules increases due to receipt of this ion connected with anion; which unlike chloride cannot reabsorbirovatsya (for example, sodium sulfate or karbenitsillin-sodium); that the only way on which sodium can reabsorbirovatsya consists in its exchange for potassium ions or hydrogen. If Aldosteronum is delivered in large numbers, intensity of this exchange increases.

The sodium reabsorption which leads to formation of negative electric potential on a surface of an epithelium of a gleam of collective tubules belongs to the mechanisms promoting an exchange of ions in this part of nephron. Thanks to existence of negative electric potential in a gleam of a collective tubule there is a movement generally of positively charged ions. Therefore, use of compounds of sodium with we nereabsorbiruyushchitsya by anion in certain circumstances can lead to development of a gipokaliyemichesky metabolic alkalosis (tab).

Influence of renal factors on a potassium homeostasis

Factor

Influence on
excretion

Influence on
potassium concentration in blood serum

Insufficiency of Aldosteronum

Change of delivery of sodium in collective tubules owing to:

 

 

increases in volume of the circulating blood

congestive heart failure

Change of a potential difference and gleam
collective tubules:

 

 

Increase

The reduction caused acceptance of amiloride or Aldactonum

Treatment:

 

 

Nereabsorbiruyemy anions

Karbenitsillniom or NaSO4

Reduction of amount of nephrons owing to a chronic renal failure

Adaptive ↑

He influences

Other important factor influencing secretion of potassium in collective tubules is adaptation of an organism to potassium which more detailed discussion is given below.

Potassium role in regulation of a hormonal exchange

Aldosteronum is the important factor influencing potassium excretion, and in turn amount of the potassium which is contained in an organism exerts impact on synthesis of Aldosteronum. There is feedback between the content of potassium in an organism and the level of synthesis of Aldosteronum. At accumulation in a potassium organism owing to its direct impact on cells of a glomerular zone of adrenal glands there is an increase of intensity of synthesis of Aldosteronum. The increase in quantity of the circulating Aldosteronum resulting from it promotes potassium excretion which in turn leads to reduction of its contents in an organism. Reduction of content of potassium leads to suppression of synthesis of Aldosteronum.

The considerable interrelation exists also between potassium and insulin. Increase in secretion of insulin promotes movement of potassium from extracellular liquid in intracellular. Moreover, potassium regulates intake of insulin in blood. The hypopotassemia leads to an insulin exit delay from a pancreas; owing to this mechanism there is a disturbance of digestion of glucose which is quite often found at patients, is long receiving diuretics. Therefore, the crucial role in regulation of a potassium exchange is played by two hormones. Aldosteronum controls potassium secretion by kidneys while insulin controls redistribution of potassium through cellular membranes. If the patient has a disease connected with deficit" both hormones it is the most probable that in this case the hyperpotassemia will be its main symptom. As it will be visible in the subsequent, clinical manifestation of deficit of both hormones is the hypoaldosteronism which most often arises at diabetics (tab).

 

The factors regulating a homeostasis of the qadi due to movement through a cellular membrane

Factor

Effect

Influence on
content of potassium in blood serum

Lack of insulin  (diabetes mellitus)

Movement To in a cell

Treatment  by beta and adrenergic

 

Movement To in a cell

Acute acidosis

Movement To from a cell

 

Alkalosis, metabolic or respiratory

 

Movement To in a cell

Adaptation to various level of intake of potassium

Kidneys and all organism, possess ability to adapt to change of intake of potassium, however origins of this adaptation are not found out yet. At significant increase in amount of the potassium arriving with food adaptable mechanisms, as a result sudden receipt of a large amount of potassium which in a usual situation, could be deadly can turn on, it is transferred without adverse effects. Kidneys adapt to increase in consumption of amount of potassium by increase of speed of its excretion. Besides, the extrarenal mechanisms increasing ability of passing of potassium in a cell turn on. The described processes of adaptation to potassium are most expressed in lower parts of a digestive tract.

Hyperpotassemia

The diagnosis of a hyperpotassemia is made at serumal potassium concentrations, exceeding 5,5 mmol/l. As it is provided in the table, this syndrome can be result of change of the general content of potassium in an organism or relative redistribution of potassium between inside - and extracellular spaces. Increase of a catabolism and destruction of cells (for example, rabdomioliz) usually are followed by a hyperpotassemia owing to a potassium exit from fabrics in extracellular space.

Hyperpotassemia reasons

Reasons

Contributing

 

Excess    consumption of substitutes of table salt or treatment of KSL

Diseases of kidneys

Anamnesis

Giparosmolarnost of blood or
lack of insulin

Diabetes mellitus

The anamnesis, clinical symptoms, osmolarity of blood serum, content of glucose in blood

Lack  of catecholamines

Diabetes mellitus

Signs of blockade or dysfunction
sympathetic nervous system

Hemolysis

    Drug intake,
sickemia

Anamnesis, detection of crescent
erythrocytes in a blood smear

Disintegration of fabrics

Rabdomioliz

Muscular pains, determination of activity of a kreatinfosfokinaza, analysis

Insufficiency
Aldosteronum

Addison's illness

Anamnesis, content in sodium blood.
cortisol and Aldosteronum

The selection insufficiency of Aldosteronum

  Diabetes mellitus,
intersticial nephrite

The anamnesis,  moderately expressed renal failure, metabolic acidosis; content in blood of potassium, renin, Aldosteronum

Use of kaliysberegayushchy

Diseases of kidneys

Anamnesis, serumal concentration
urea nitrogen and creatinine

Decrease in delivery
sodium in collective tubules

Reduction of volume I circulate -
 blood Russian cabbage soup,    sodium delay
(congestive  heart  failure)

The anamnesis, clinical symptoms, content of sodium in urine

Renal canalicular acidosis

Obstruction  of urinary tract

The anamnesis, clinical symptoms, moderately expressed renal failure, rn urine, contents
potassium and Aldosteronum in serum
blood and in urine



 
Hypercalcemia"