Hypokalemia (Abnormally Low Potassium Levels): Everything You Need To Know

Our bodies are so intricately designed, so precise, and delicate that even the most seemingly insignificant change can have serious repercussions. In the milieu of chemicals that regulate our various functions, one very important yet quite unpopular element is potassium. A whopping 98% of our body’s potassium is found inside our cells. The remaining meager 2% is distributed outside cells – in blood vessels, lymph vessels, and the spaces between cells.As an essential mineral, potassium serves numerous functions in the body, from maintaining the blood pressure and helping the heart pump to helping nerves transmit signals and muscles contract.

[pullquote]

• Normal potassium: 3.5–5.0 meq/L
• Hypokalemic potassium: <3.5 meq/L
• Panic situation: <2.5 meq/L

[/pullquote]

When the potassium levels in the body fall below the normal (<3.5 meq/L), it leads to hypokalemia. This metabolic disorder does not occur on its own but as a symptom or side effect of another underlying disorder. It is more common in women than in men, in African-Americans, and in individuals over 65 years of age.¹ With the help of aldosterone, an adrenal hormone, usually, our kidneys excrete nearly 90% of the potassium we consume maintaining the narrow optimal range of potassium in the blood (3.5–5.0 meq/L).² Here’s a look at the symptoms of hypokalemia.

Symptoms Of Hypokalemia Manifest Mostly In Muscular Problems

Hypokalemia is mostly asymptomatic or symptoms are too mild to notice. Because of this, you will not know your potassium levels are low before you do a routine blood test or electrocardiogram. Also, there will never be a single symptom but a combination of symptoms.

[pullquote]Seek medical help if:

 

• You have been continuously vomiting
• Your stomach has been upset for a long time
• You notice symptoms of hypokalemia while you are on diuretics[/pullquote]

Keeping in mind the need for potassium in muscles, nerves, bones, blood, and the digestive system, it is easy to apprehend the consequences of its deficiency. Most symptoms of hypokalemia are because of problems in muscle contractions whether in the heart, blood vessels, gut, or lungs. They may also be due to side effects of other medical conditions or medications. Symptoms include:^{3 4}

• Constipation
• Muscle twitches
• Cramps during exercise
• Extreme muscle weakness
• Slow or shallow breathing
• Excessive urination (polyuria)
• Excessive thirst (polydipsia)
• Loss of appetite
• Distended belly
• Confusion
• Decreased mental activity
• Overall weakness and fatigue
• Low blood pressure

A big drop in blood potassium can cause irregular heart rhythms and lightheadedness. In extreme cases, it may even cause cardiac arrest.⁵

If potassium is low in the muscles of the heart or lungs during attacks of thyrotoxic periodic paralysis (a muscle disorder), a person may die.^{6 7}

Hypokalemia Is Mostly Caused By The Loss Of Potassium From The Body

Through The Gastrointestinal System

Potassium may be lost from the stomach and intestines because of:

• Prolonged diarrhea
• Chronic laxative abuse as a form of bulimia
• Inflammatory bowel diseases
• GI tract infections
• Persistent vomiting
• Intestinal fistulas which deplete intestinal fluids
• Uterosigmoidostomy (a urinary tract surgery)⁸
• Salt-losing nephropathy (inherited defects in kidney tubules)⁹

Through Urine

Considering the critical role the kidneys play to maintain blood potassium levels within a narrow range, any interference in kidney function is bound to snowball into hypokalemia. Potassium may be lost via urine because of:

• Diuretic drugs like loop diuretics and thiazide diuretics¹⁰
• Polyuria (kidney disorder causing excessive urination)
• A deficiency of magnesium in the blood (a common side effect of alcohol withdrawal)^{11 12}
• Excessive mineralocorticoids (aldosterone and cortisol)
• High doses of penicillin-related antibiotics (nafcillin, dicloxacillin, ticarcillin, oxacillin, and carbenicillin)¹³

Through Perspiration

A very small amount of potassium is lost through sweat. A person may sweat excessively because of:

• Hot weather
• Strenuous exercise

Movement Of Potassium Into Cells May Also Lower Blood Potassium Levels

Potassium may move into cells from intercellular spaces and blood because of several factors and thereby cause hypokalemia. Certain sections of the population are more at risk than others – for instance, patients of type 1 diabetes who take insulin injections, people with B12 deficiency who take folic acid, people who suffer from hyperthyroidism, or people who have undergone heart attacks.

• Excess insulin: People with type 1 diabetes don’t have enough insulin so they inject themselves with it. While insulin helps lower their blood sugar levels, it also activates the sodium-potassium pumps and increases uptake of potassium into cells.¹⁴ This makes potassium levels outside cells lower than normal.
• Alkalosis: Alkalosis is the condition where the concentration of hydrogen ions in the blood is low. To compensate, cells pump out hydrogen ions into the blood in exchange for potassium ions. This lowers blood potassium levels. Use of high doses of the drug penicillin causes alkalosis and, hence, hypokalemia.¹⁵
• Hormones: Catecholamines, a type of adrenal hormones can manipulate cellular sodium-potassium pumps to favor potassium secretion into the urine. More potassium urinated means higher risks of hypokalemia.¹⁶
• Increased RBC production: Folic acid administration in B12-deficient individuals increases red blood cells (RBC) production. These new cells leach potassium out of the blood and internalize it.¹⁷
• Change in activity of the sympathetic nervous system: Alcohol withdrawal, hyperthyroidism (excess thyroid hormone), acute myocardial infarctions (heart attacks), and severe head injuries can affect your body’s involuntary responses, promoting the influx of potassium into cells.¹⁸

Hypokalemia Is Also A Side Effect Of Some Diseases

Hypokalemia is often a symptom of another disorder, putting individuals suffering from such disorders at an increased risk of low blood potassium.¹⁹ These include:

• Bartter Syndrome: This heritable kidney disorder increases aldosterone levels, which in turn forces the kidneys to excrete more potassium.²⁰
• Gitelman Syndrome: Another heritable kidney disorder, Gitelman syndrome involves a mutation in the kidneys that increases potassium secretion into urine.²¹
• Cushing’s Syndrome: By increasing the hormone cortisol levels, Cushing’s syndrome can promote loss of potassium in urine.²²
• Hypokalemic periodic paralysis: This muscle disorder causes potassium to move out of the blood and into muscle cells.²³
• Metabolic alkalosis: Sharing common causes with hypokalemia like vomiting and diuretics, metabolic alkalosis (an increase in the pH of tissues) induces potassium loss from the body.²⁴

Inadequate Potassium Intake Through Food Leads To Hypokalemia In Rare Cases

Though the average American diet is low in potassium and most people do not get the daily recommended amount of 4700 mg, hypokalemia caused by poor dietary intake is rare. Because most foods contain potassium, it is unlikely that the potassium levels drop so low as to cause hypokalemia. However, we also need to constantly supply our bodies with potassium. When we fail to do so, we are putting ourselves at a risk of hypokalemia. We may not consume enough potassium because of prolonged fasting, anorexia, or eating a specific, restricted diet or skipping fresh produce entirely. The top food sources of potassium are mostly fresh and dried fruits and veggies. Eating too much licorice has also been implicated in lowering potassium levels below normal.²⁵

Women, African Americans, And The Elderly Are More At Risk

The factors that put certain individuals at a higher risk of hypokalemia are:

• Chronic illnesses that cause vomiting or diarrhea²⁶
• Intake of certain drugs (diuretics, laxatives, or penicillin-related antibiotics)²⁷
• Female gender²⁸
• African-American origin²⁹
• Old age (over 65 years)³⁰

Treatment Involves Stopping Potassium Loss And Restoring The Levels

If you notice any of the symptoms of hypokalemia, get yourself checked. Your healthcare provider will first study your medical history, diet, and other possible causes.³¹ If the cause doesn’t look obvious, regular blood tests will be run to measure your blood potassium and magnesium levels. Your urine potassium may also be measured. An electrocardiogram may help further discern whether or not your potassium levels are low.

[pullquote]

• If you know you have hypokalemia, avoid strenuous activity to minimize potassium loss through sweat.
• Don’t stop taking any medications, like diuretics, that seem to be responsible. Consult your doctor first.[/pullquote]

On identifying low levels of potassium, the underlying cause must be addressed first. When drafting a treatment plan, associated acid-base disorders or hormonal disturbances must be taken into consideration.³²

There are two basic approaches to treating hypokalemia:

Potassium Restoration

• Oral or intravenous administration of potassium chloride: This is advised only in cases of severe hypokalemia. Most patients take potassium chloride orally, preferably with food to avoid an upset stomach. Intravenous administration generally causes burning pain in the vein.
• Intake of potassium-rich foods or drugs: Individuals on diuretics who have high blood pressure can normalize their blood potassium by consuming potassium-rich foods (like soybean, prunes, dark leafy greens, tuna, and yogurt) or potassium drugs. Individuals who exercise extensively in hot weather can also benefit from dietary potassium.

The degree of urgency to replenish your body’s potassium levels will depend on how fast your hypokalemia developed and whether your hypokalemia is a symptom of another more serious condition (QT prolongation, active coronary ischemia).³³

Caution needs to be exerted in cases of hypokalemic periodic paralysis (a muscle disorder) because potassium levels can swing to the opposite end of the spectrum causing hyperkalemia (excess potassium in the blood).

Prevention Of Further Potassium Loss

• Restriction of salt intake: The more salt you eat, the more sodium is excreted in urine. High sodium excretion favors more potassium excretion. Limiting your salt intake can avoid this problem.
• Prescription of potassium-sparing diuretics for those already on diuretics: Such diuretics do not promote secretion of potassium into the urine, restoring normal blood potassium levels. However, all diuretics are advised against in individuals suffering from kidney disease, diabetes mellitus, or autonomic nervous system disorders.

With careful dietary planning, you can significantly reduce your risks of hypokalemia. If you are using laxatives or diuretics, consult your doctor to make sure your potassium levels don’t take a hit. Those with low potassium levels should keep an eye out for sweat-related potassium loss due to strenuous physical activity, particularly in hot weather.