Less than 3.5 meq/L blood potassium indicates hypokalemia. Blood potassium can reach such lows due to chronic vomiting, diarrhea, frequent urination, and to some extent even sweating. Watch out for constipation, muscle cramps, shallow breathing, and overall weakness and fatigue. Be extra careful if you are on diuretics. Dietary planning can help reduce your risks of hypokalemia.
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 walloping 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. Sodium-potassium cellular pumps help create this concentration difference.
What Is Hypokalemia?
Hypokalemia is a metabolic disorder where there is lower than normal potassium levels in the blood (<3.5 meq/L). It is not a disorder that occurs 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
- Normal potassium: 3.5–5.0 meq/L
- Hypokalemic potassium: <3.5 meq/L
- Panic situation: <2.5 meq/L
Why Do We Need Potassium?
Our muscles need potassium to contract. Out of the 2% of our total body’s potassium, 80% is in our skeletal muscles.
- To transmit nerve signals: Because potassium is positively charged and there is more inside our cells than outside, an electrical gradient is created across cell membranes, including those of nerve cells. Nerve signals are transmitted using these gradients.
- To contract muscles: Potassium helps transport calcium into cells via sodium-potassium pumps, helping muscles contract (including smooth, cardiac, and skeletal muscles) and bones strengthen.2
Your body needs potassium to function normally, making this nutrient an important one, down to every last cell. It’s also essential in maintaining normal body growth.
How Does Our Body Maintain Potassium Levels?
Our kidneys excrete nearly 90% of the potassium we consume. Though this may seem counterproductive knowing how important potassium is for us, maintaining the narrow optimal range of potassium in the blood (3.5–5.0 meq/L) is what matters.
Our kidneys decide how much potassium is retained in the body and how much is excreted (through urine). Aldosterone, an adrenal hormone, helps the kidney perform this function. More aldosterone means more potassium excreted and lower levels of potassium in the blood.3
Causes Of Hypokalemia
1. Inadequate Consumption Of Potassium
We 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
- Specific diets
Because potassium is so abundant in foods, even if we don’t eat enough, it is very rare that our potassium levels drop so low as to cause hypokalemia.
2. Extensive Loss Of Body Fluids
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)4
- Salt-losing nephropathy (inherited defects in kidney tubules)5
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 in urine because of:
- Diuretic drugs like loop diuretics and thiazide diuretics6
- Polyuria (kidney disorder causing excessive urination)
- A deficiency of magnesium in the blood (a common side effect of alcohol withdrawal)7 8
- Excessive mineralocorticoids (aldosterone, cortisol)
- High doses of penicillin-related antibiotics (nafcillin, dicloxacillin, ticarcillin, oxacillin, and carbenicillin)9
A very small amount of potassium is lost through sweat. A person may sweat excessively because of:
- Hot weather
- Strenuous exercise
3. Movement Of Potassium Into Cells
Potassium may move into cells from intercellular spaces and blood because of:
- Excess insulin: People with type I 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.10 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.11
- Catecholamines: These adrenal hormones can manipulate cellular sodium-potassium pumps to favor potassium secretion into the urine. More potassium urinated means higher risks of hypokalemia.12
- Increased RBC production: Folic acid (vitamin B12) administration in B12-deficient individuals increases red blood cells (RBC) production. These new cells leach potassium out of the blood and internalize it.13
- 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.14
Symptoms Of Hypokalemia
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
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.
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 (heart, blood vessels, gut, or lungs). They may also be due to side effects of other medical conditions or medications. Symptoms include15 16:
- Muscle twitches
- Cramps during exercise
- Extreme muscle weakness
- Slow or shallow breathing
- Excessive urination (polyuria)
- Excessive thirst (polydipsia)
- Loss of appetite
- Distended belly
- 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.17
If hypokalemia occurs during attacks of thyrotoxic periodic paralysis (a muscle disorder) and potassium is low in the muscles of the heart or lungs, a person may die.18 19
The factors that put certain individuals at a higher risk of hypokalemia are:
- Chronic illnesses that cause vomiting or diarrhea20
- Intake of certain drugs (diuretics, laxatives, penicillin-related antibiotics)21
- Female gender22
- African-American origin23
- Old age (over 65 years)24
Hypokalemia is often a symptom of another disorder, putting individuals suffering from such disorders at an increased risk of low blood potassium.25 These include:
- Bartter Syndrome: This heritable kidney disorder increases aldosterone levels, which in turn forces the kidneys to excrete more potassium.26
- Gitelman Syndrome: Another heritable kidney disorder, Gitelman syndrome involves a mutation in the kidneys that increases potassium secretion into urine.27
- Cushing’s Syndrome: By increasing the hormone cortisol levels, Cushing’s syndrome can promote loss of potassium in urine.28
- Hypokalemic periodic paralysis: This muscle disorder causes potassium to move out of the blood and into muscle cells.29
- 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.30
If you notice any of the symptoms of hypokalemia, get yourself checked. Your healthcare provider will first study your medical history31:
- Medications (laxatives, diuretics, antibiotics)
- Diet and dietary habits (licorice)
- Symptoms that suggest a particular cause (periodic weakness, diarrhea).
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.
- 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.
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:
1. 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).
2. 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.
References [ + ]
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|2, 12.||↑||Cheng, Chih-Jen, Elizabeth Kuo, and Chou-Long Huang. “Extracellular potassium homeostasis: insights from hypokalemic periodic paralysis.” In Seminars in nephrology, vol. 33, no. 3, pp. 237-247. WB Saunders, 2013.|
|3.||↑||Palmer, Lawrence G., and Gustavo Frindt. “Aldosterone and potassium secretion by the cortical collecting duct.” Kidney international 57, no. 4 (2000): 1324-1328.|
|4.||↑||Stein, Raimund, and Peter Rubenwolf. “Metabolic consequences after urinary diversion.” Frontiers in pediatrics 2 (2014).|
|5.||↑||Singh, N. P., Gurleen Kaur, and Anupam Prakash. “Inherited salt-losing renal tubulopathies manifesting as normotensive hypokalemic metabolic alkalosis.” JAPI 58 (2010): 283.|
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|10.||↑||Choi, Hoon Young, and Sung Kyu Ha. “Potassium balances in maintenance hemodialysis.” Electrolytes & Blood Pressure 11, no. 1 (2013): 9-16.|
|11.||↑||Zaki, Syed, and Preeti Shanbag. “Meropenem-induced hypokalemia and metabolic alkalosis.” Indian journal of pharmacology 44, no. 2 (2012): 276.|
|15, 20, 21, 25, 32.||↑||Hypokalemia. National Organization for Rare Disorders.|
|16.||↑||Webster, D. R., H. Winter Henrikson, and D. J. Currie. “The effect of potassium deficiency on intestinal motility and gastric secretion.” Annals of surgery 132, no. 4 (1950): 779.|
|17, 18.||↑||Low Potassium Level. University of Maryland Medical Center.|
|19.||↑||Kung, Annie WC. “Thyrotoxic periodic paralysis: a diagnostic challenge.” The Journal of Clinical Endocrinology & Metabolism 91, no. 7 (2006): 2490-2495.|
|22, 24.||↑||Kleinfeld, Morris, Sonia Borra, Sobha Gavani, and Anthony Corcoran. “Hypokalemia: are elderly females more vulnerable?.” Journal of the National Medical Association 85, no. 11 (1993): 861.|
|23.||↑||Andrew, Michael E., Daniel W. Jones, Marion R. Wofford, Sharon B. Wyatt, Pamela J. Schreiner, C. Andrew Brown, David B. Young, and Herman A. Taylor. “Ethnicity and unprovoked hypokalemia in the Atherosclerosis Risk in Communities Study.” American journal of hypertension 15, no. 7 (2002): 594-599.|
|26.||↑||Bartter Syndrome. U.S. National Library of Medicine.|
|27.||↑||Gitelman Syndrome. U.S. National Library of Medicine.|
|28.||↑||Torpy, David J., Nancy Mullen, Ioannis Ilias, and Lynnette K. Nieman. “Association of hypertension and hypokalemia with Cushing’s syndrome caused by ectopic ACTH secretion.” Annals of the New York Academy of Sciences 970, no. 1 (2002): 134-144.|
|29.||↑||Hypokalemic Periodic Paralysis. U.S. National Library of Medicine.|
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