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What causes low magnesium and potassium?

The short answer:

The main causes of low magnesium and potassium blood levels include low intake, increase loss through the kidney, and medications-induced low magnesium and potassium blood levels. Find more about the most common causes of low magnesium and potassium in this article.

Key facts:

  • Magnesium and potassium represent important elements that play important roles in numerous biological functions.
  • Lager number of medications are reported to cause low magnesium and potassium blood levels.
  • Low potassium and magnesium intake play a role in their lower blood levels.
  • The loss of potassium and magnesium through the kidneys due to medications or diseases has a major role in lowering blood levels.


What are the main functions of magnesium in your body?

Magnesium is a chemical element that has the symbol (Mg). It is the fourth most abundant cation element in your body.

Magnesium is an important element for numerous biological functions including:

  • It has an important role as a cofactor for more than 300 enzymatic reactions.
  • It regulates a number of fundamental functions in your body systems such as muscle contraction, neuromuscular conduction, glycemic control, myocardial contraction, and blood pressure (Ref).
  • Also, magnesium plays a vital role in energy production, active transmembrane transport for other ions, and synthesis of nuclear materials (Ref).
  • It has an important role in your bone development.

What does a low magnesium level mean?

The normal magnesium blood levels are between 1.46 and 2.68 mg/dL.

Hypomagnesemia means your magnesium serum level is less than 1.46 mg/dL (Ref). It remains asymptomatic until the magnesium blood level is less than 1.2 mg/dL (0.5 mmol/L).

The total body magnesium in the average adult is around 1000 mmol or 24 g.

According to the United States Food and Nutrition Board, the recommended daily allowance for magnesium is 420 mg for adult males and 320 mg for adult females (Ref).

About 10% of the daily magnesium requirement is derived from water. Also, green vegetables, nuts, seeds, and unprocessed cereals are rich sources of magnesium. In addition, some magnesium is available in fruits, fish, meat, and milk products

Your bones store about 50–60% of your total magnesium content. While your muscles and other soft tissues store around 40–50%. Around one-third of the bone magnesium content is available for exchange to maintain the levels of extracellular magnesium.

Less than 2% of the total magnesium in the body is available in serum and red blood cells, they account for the extracellular magnesium in your body (Ref).

What are the main causes of low magnesium blood levels?

The mean causes of low magnesium blood levels are the following:

Decreased magnesium intake

Many studies reported that people in North America and Europe consume less than recommended daily allowance (RDA) for magnesium due to food processing and the use of poor soil for agriculture.

Also, the majority of the population in Western countries consumes less than the recommended amount of magnesium leading to hypomagnesemia. This may be attributed to the consumption of processed foods, demineralized water, and agricultural practices using soil deficient in magnesium for growing food

In addition, decreased magnesium intake was reported for individuals with prolonged starvation, and patients with prolonged total parenteral nutrition (Ref).

Gastrointestinal absorption problems:

The decrease in gastrointestinal absorption of magnesium can results from a number of factors including

  • Chronic diarrhea
  • Chronic alcoholism
  • Pancreatic insufficiency
  • Inflammatory bowel diseases
  • Short gut syndrome

In a study involving 127 patients with chronic alcoholism, 20 out of 38 cases of hypomagnesemia were thought to be due to alcohol withdrawal syndrome and diarrhea.

What are the medications that cause low magnesium blood levels?

What drugs can cause low magnesium levels?

There are about 50 medications that are reported to decrease the magnesium level in your body

Here is a list of some of these medications(Ref):

  • Proton pump inhibitors such as omeprazole
  • Diuretics (loop and thiazide diuretics)
  • Aminoglycosides antibiotics
  • Pentamidine
  • Platinum derivatives (e.g., cisplatin and carboplatin)
  • Cyclosporine and tacrolimus
  • Cetuximab

What diseases cause low magnesium blood levels?

Several diseases could lead to a decrease in magnesium levels.

These diseases include:

  • Diabetes mellitus
  • Acute tubular necrosis,
  • Post obstructive diuresis,
  • Post kidney transplantation
  • Chronic metabolic acidosis
  • Chronic alcoholism
  • Crohn’s syndrome

Most of these diseases cause increased magnesium hyperfiltration and increased renal loss of magnesium.

What are the main functions of potassium in your body?

Potassium is a chemical element that has the chemical symbol (K). You have to differentiate between potassium (K) and vitamin K. Usually vitamin K is written as vitamin K, not the K symbol only.

Potassium is the most abundant cation in the human body

Important functions of potassium in your body:

  • Potassium is an important electrolyte for cell function, particularly in excitable tissues, such as nerves, and cardiac, and skeletal muscles (Ref).
  • Important for maintaining normal fluid levels in the cells.
  • It also plays a role in controlling fluid levels outside the cells.
  • It helps muscle contraction.
  • Important for normal blood pressure
  • Regulate heart rate.
  • It has a vital role in protein synthesis and carbohydrate metabolism.

What does a low potassium blood level mean?

Low potassium blood levels are referred to as hypokalemia.

The normal blood levels of potassium range from 3.5 to 5.2 mmol/L.

Hypokalemia means your potassium blood level is lower than 3.5 mmol/L (Ref).

Severe and life-threatening hypokalemia occurs when your potassium blood levels are lower than 2.5 mmol/L (Ref).

The prevalence of hypokalemia in hospitalized patients is between 6.7% and 21%.

The current recommendations define the standard lower potassium limit from 3.5 to 3.8 mmol/L and the upper limit from 5.0 and 5.5 mmoL (Ref).

What are the main causes of low potassium blood levels?

The main causes of low potassium blood levels include the following

Low potassium intake

  • Poor potassium intake in your diet
  • Low Calories diet

Gastrointestinal loss

Increased potassium loss through the gastrointestinal route could be due to

  • Vomiting
  • Chronic diarrhea
  • Chronic laxative abuse
  • Intestinal obstruction
  • Intestinal infections

Renal loss

Renal potassium loss (kaliuresis) could be due to the following:

  • Diuretics (Approximately 80% of patients who are receiving diuretics become hypokalemic)
  • Renal tubular acidosis
  • Medications
  • Hypomagnesemia
  • Chronic kidney diseases

Medications induced low potassium blood levels

What drugs can cause low potassium levels?

Several medications could decrease your blood potassium level such as the following (Ref):

  • Thiazides
  • Loop diuretics
  • Osmotic diuretics
  • Laxatives
  • Amphotericin B
  • Penicillin
  • Theophylline
  • Ephedrine
  • Terbutaline
  • Albuterol

Diseases-induced low potassium blood levels

Many diseases lead to lower potassium levels including the following diseases

  • Diabetes
  • Hypomagnesemia
  • Chronic kidney disease
  • Folic acid deficiency
  • Primary hyperaldosteronism
  • Adrenal steroid excess (Cushing’s syndrome
  • Chronic kidney diseases
  • Alcoholism

Interestingly, a recent study reported a high prevalence of hypokalemia among patients with COVID-19.


1. Is there a relationship between hypokalemia and hypomagnesemia?

Concomitant magnesium deficiency has long been appreciated to aggravate hypokalemia

Studies showed that more than 50% of patients with clinically significant hypokalemia have a concomitant hypomagnesemia

The condition of both concomitant hypokalemia and hypomagnesemia is most frequently observed in individuals receiving loop or thiazide diuretic therapy.

2. Do potassium and magnesium have an inverse relationship?

No, there is no inverse relationship between magnesium and potassium blood levels. However, decrease magnesium blood level is reported to trigger potassium loss leading to hypokalemia.

It is reported that magnesium deficiency enhances potassium loss by increasing distal potassium secretion (Ref).

However, magnesium deficiency alone does not necessarily cause a low potassium blood level.