Generality
Potassium is an essential mineral for our body; in fact, it plays an important role in maintaining the hydro-saline balance and is the basis of important neuromuscular and cardiac functions.
A too high potassium level in the blood also has very serious health consequences, especially with regard to the heart, the musculoskeletal system and the nervous system.
What's this
Potassium and biological role
Potassium is a mineral salt involved in various physiological processes within the body.
Did you know that ...
In Latin, potassium was called "kalium". For this reason, pathologies involving this element often contain "kal" in the name.
Along with calcium and sodium, potassium performs several important functions, including:
- Maintains the electric membrane potential of cells, necessary for the conduction of nerve impulses and muscle contraction;
- Inside the cells, it regulates the acid-base balance (ie the pH) and the osmotic pressure;
- Promotes the action of enzymes involved in cellular metabolism;
- Contributes to the maintenance of a normal heart rhythm;
- Participate in maintaining normal blood pressure, dampening the effects of sodium;
In the body, in resting conditions, most of the potassium is found inside the cells (while sodium and calcium are predominantly extracelullary).
The intracellular potassium concentration is maintained by means of an active transport system (called sodium-potassium pump), which transports the sodium outside the membrane, causing potassium to re-enter.
Potassium is introduced into the body through the diet, but, to maintain its levels within the normal range, the body can resort to the reserves of the element located inside the cells, depending on the needs of organs and tissues .
In any case, the body is not able to self-produce potassium; for this reason, it is advisable to regulate intake with the diet. The kidneys, then, will intervene in the event that it is necessary to increase the excretion or reabsorption of the mineral. A small amount of potassium is eliminated in the faeces.
Hyperkalemia: definition
Hyperkalemia (or hyperkalemia ) is defined as a serum potassium concentration equal to or greater than 5.5 mEq / l . This condition can be caused by excessive reserves of this element in the body (due to increased food intake or reduced renal elimination) or by an abnormal displacement of the same outside the cells.
The causes of hyperkalemia may be exogenous or endogenous. In any case, the alteration of potassium homeostasis is potentially lethal and requires immediate medical intervention.
Why do you measure
The potassium test is indicated to verify the possible variation of the potassium, that is the level of the element present in the blood.
This evaluation is required when the doctor suspects an acid-base or hydrosaline imbalance, or when the main clinical effects of the excess potassium are found, represented by alterations of cardiac conduction, arrhythmias, muscle weakness and tremors.
Measurement of potassium in the blood must also be performed periodically by dialysis patients: although potassium is efficiently filtered, it accumulates rapidly in the body between one treatment and another. Therefore, these people must be very careful not to introduce too much potassium with the diet.
The evaluation of potassium is carried out at regular intervals even in the case of taking certain drugs (eg diuretics) or in the presence of pathologies (in particular, kidney diseases and arterial hypertension) that can cause changes in the potassium.
When is the exam prescribed?
Potassium is often evaluated as part of routine analyzes to check general health status.
The doctor may indicate this assessment even in cases where the patient suffers from hypertension or shows symptoms of hyperkalaemia (or hyperkalemia). Furthermore, the examination is prescribed in the presence of heart failure and kidney failure.
Normal values
- The potassium concentration in the blood is optimal if it is between 3.5 and 5.0 mEq / l. The value depends on several factors, including: hormones, blood pH, dietary intake and renal function; it is also influenced by the circadian rhythm.
- Values above 5.0 mEq / l indicate hyperkalaemia (hyperkalemia). In particular, the following is considered:
- Mild hyperkalemia : values between 5.0 and 5.9 mEq / l;
- Moderate hyperkalemia : 6.0-6.4 mEq / l;
- Severe hyperkalemia :> 6.5 mEq / l.
A potassium that reaches values of 10 mEql / l is incompatible with life.
During renal insufficiency, due to the reduced capacity of the organ to correctly eliminate potassium, hyperkalaemia with blood levels higher than 5.5 mEq / l occurs more frequently.
- Values lower than 3.5 mEq / l indicate hypokalaemia (hypokalemia).
Potassium in High Blood - Causes
High blood potassium can occur under the following conditions:
- Reduced renal function (nephropathy, acute and chronic insufficiency, tubular acidosis, etc.);
- Increased intake of foods high in potassium, fasting and relative insulin deficiency;
- Urinary obstruction;
- Hyperglycemia and decompensated diabetes mellitus;
- Diabetic ketoacidosis;
- Addison's disease;
- hypoaldosteronism;
- Systemic lupus erythematosus;
- Sickle cell anemia;
- Digital toxicity;
- Infections;
- Dehydration;
- Intense physical effort;
- Red cell abnormalities, thrombocytosis and leukocytosis.
Hyperkalemia may depend on an increased tissue catabolism, as happens in the case of:
- Soft tissue or gastro-intestinal tract bleeding;
- Acute intravascular hemolysis;
- Massive cell death and tissue necrosis;
- Tumor lysis syndrome.
An excess of potassium is frequent in the presence of:
- Cellular mechanical damage;
- Muscle decomposition (rhabdomyolysis);
- Severe burns;
- Adrenal insufficiency;
- Crushing trauma.
The increase in potassium can also occur due to iatrogenic causes, such as massive blood transfusion, chemotherapy and intake of supplements or drugs containing potassium salts (eg penicillin G or potassium phosphate).
Other medicines that frequently cause hyperkalemia are:
- Diuretics (such as triamterene and spironolactone);
- Non-steroidal anti-inflammatory drugs (eg ibuprofen and diclofenac);
- Angiotensin receptor blockers (eg losartan);
- Ciclosporin and tacrolimus (drugs used to prevent transplant rejection);
- β-blockers (such as atenolol);
- ACE inhibitors (ramipril, captopril, etc.)
- Sartans (which antagonize the effects of aldosterone in the excretion of potassium).
Possible associated symptoms
The clinical manifestations of hyperkalemia are generally neuromuscular and include:
- Asthenia (fatigue) progressive up to flaccid paralysis;
- Breathing difficulties;
- paresthesia;
- Weakness and muscle cramps;
- Sensation of heavy legs;
- Abdominal pain with nausea, vomiting and diarrhea.
The most important damage occurs at the level of the heart, which is subjected to "high current discharge". This phenomenon can degenerate into heart rhythm disorders, such as arrhythmias, slow heart beats and / or ventricular fibrillation up to asystole and cardiac arrest.
How to measure it
The potassium test is a laboratory analysis that is performed after a simple blood test.
Preparation
No special preparation rules are required before undergoing potassium testing. Fasting is recommended, although not necessary. However, it is necessary to remember to tell the doctor which type of drug therapy you are following, as many medicines can influence the outcome of the analysis.
Also the method used to perform the collection and examination can influence the levels of potassium. Among the factors that can cause high potassium values for an incorrect execution of the analysis are above all:
- Too tight tourniquet;
- Patients who open and close their fist forcefully during collection;
- Samples analyzed late;
- Blood collection too quickly in the tube.
In this case, the doctor should consider very carefully whether and how to repeat the assessment of the potassium.
Interpretation of Results
An increase in potassium may occur in different conditions, including: kidney disease, decompensated diabetes mellitus, hypoaldosteronism and dehydration.
Among the most frequent causes of a high potassium in the blood must also be remembered the taking of drugs, such as ACE inhibitors, diuretics and sartans. Hyperkalemia exposes you to the risk of severe rhythm disturbance or cardiac conduction.
Potassium High in the Blood: Possible Causes | |
Increased contribution |
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Decreased excretion in urine |
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Potassium release from cells |
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In any case, the results of the analysis must be assessed as a whole by the general practitioner, who knows the patient's medical history. The therapeutic management of hyperkalemia depends on its severity and its mechanism.
Treatment may include:
- Reduction of dietary intake of potassium;
- Suspension of therapies that cause hyperkalemia;
- Use of drugs to increase potassium excretion.
How to control potassium in the blood
- In the event of hyperkalaemia, the doctor may prescribe ion exchange resins, which act in the intestine, binding the potassium contained in the food. This promotes the elimination of the element with the faeces and reduces the amount absorbed in the blood.
- Practicing regular physical activity can help eliminate potassium with sweating. There is no need to do exhausting workouts, but it is enough to take a walk or ride a bike.
- Proper nutrition helps to limit the amount of potassium introduced. In fact, this is found in most foods and beverages, including fruits and vegetables. In the case of high potassium in the blood, ketchup sauce, chocolate, biscuits, fruit, potatoes, wine, beer and coffee may be limited; it is possible to consume a portion of fresh fruit a day, while the second portion should be of cooked fruit.
In case of hyperkalemia, then, it is advisable to drastically reduce the consumption of fruit very rich in potassium (such as bananas) and dried (eg walnuts, almonds, raisins and pine nuts).
How to prepare food to lower the level of potassium
With some changes, food preparation can influence the excessive amount of potassium taken with the diet.
Before consumption, it is advisable to cut the potatoes and raw vegetables (fennel, salad, radicchio, carrots, etc.) into small pieces and dip them in plenty of warm water for about two hours, changing them at least once. In this way, a large amount of potassium will be removed (like salt, this element also dissolves in water). Then drain and cook, removing the peel when possible.
