Causes Of Hypomagnesemia

Question 1

What is a cause of hypomagnesemia related to decreased intake?

Answer 1

Protein-calorie malnutrition

Poor Mg²⁺ intake can occur due to various factors including malnutrition and prolonged intravenous therapy without magnesium supplementation.

Question 2

What are two reasons why chronic alcoholism can lead to hypomagnesemia?

Answer 2

Poor dietary intake and alcohol-induced kidney Mg²⁺ loss

Alcohol consumption can result in a combination of poor intake and increased loss of magnesium through the kidneys.

Question 3

Fill in the blank: Prolonged nasogastric suction can lead to decreased intestinal absorption of _______.

Answer 3

Mg²⁺

Question 4

What condition can lead to magnesium loss from the intestine due to malabsorption?

Answer 4

Sprue or steatorrhea

These conditions impair the absorption of nutrients, including magnesium, leading to deficiencies.

Question 5

What is one inherited disorder that causes increased urinary loss of magnesium?

Answer 5

FHHNC (CLDN16/19 mutations)

This condition results in magnesium and calcium wasting, leading to nephrocalcinosis.

Question 6

True or False: Hyperaldosteronism can lead to secondary magnesium wasting.

Answer 6

True

Question 7

What is a common drug class that can cause hypomagnesemia by inhibiting TRPM6?

Answer 7

Diuretics (loop/thiazide)

These medications affect the reabsorption of magnesium in the kidneys.

Question 8

What syndrome is associated with hypomagnesemia and hypokalemia due to genetic mutations?

Answer 8

EAST syndrome (KCNJ10 mutations)

This syndrome is characterized by electrolyte imbalances, including low magnesium and potassium levels.

Question 9

Fill in the blank: Diabetic ketoacidosis can lead to hypomagnesemia through _______.

Answer 9

osmotic diuresis

Question 10

What mechanism can cause a cellular shift of magnesium?

Answer 10

Glucose/insulin or epinephrine infusion

These conditions can lead to a temporary redistribution of magnesium into cells.

Question 11

What is the effect of burns or heavy exercise on magnesium levels?

Answer 11

Skin loss

These conditions can lead to increased loss of magnesium through sweat.

Question 12

What key takeaway summarizes the major categories of causes for hypomagnesemia?

Answer 12

Poor intake, malabsorption, kidney wasting, drugs

These categories encompass the primary reasons for magnesium deficiency.

Question 13

What genetic causes are often involved in hypomagnesemia?

Answer 13

TRPM6, claudins, or Na/K-ATPase

Mutations in these proteins can impair magnesium reabsorption and lead to deficiency.

Question 14

What common drug classes are noted as culprits for causing hypomagnesemia?

Answer 14

Diuretics, PPIs, and chemotherapy

These medications can interfere with magnesium absorption and excretion.

Question 15

What may refractory hypokalemia or hypocalcemia signal?

Answer 15

Mg²⁺ deficiency

Persistent low potassium or calcium levels can indicate an underlying magnesium deficiency.

Question 16

What is the disorder associated with CLDN16/19 mutations?

Answer 16

Familial Hypomagnesemia with Hypercalciuria & Nephrocalcinosis (FHHNC)

Inheritance is autosomal recessive.

Question 17

What is the mechanism of FHHNC due to CLDN16/19 mutations?

Answer 17

Impaired paracellular Mg²⁺/Ca²⁺ reabsorption in TALH

Ocular defects may occur with CLDN19 mutations.

Question 18

List the clinical features of FHHNC.

Answer 18

• Hypomagnesemia
• Hypercalciuria
• Progressive CKD (ESKD by adolescence)

Nephrocalcinosis and kidney stones are also common.

Question 19

What is the treatment for FHHNC?

Answer 19

• Thiazides
• Citrate for nephrocalcinosis
• Kidney transplant (curative)

Thiazides help reduce Ca²⁺ excretion.

Question 20

What disorder is associated with TRPM6 mutations?

Answer 20

Familial Hypomagnesemia with Secondary Hypocalcemia

Inheritance is autosomal dominant.

Question 21

What is the mechanism of Familial Hypomagnesemia with Secondary Hypocalcemia?

Answer 21

Impaired Mg²⁺ absorption (gut/DCT) leading to PTH suppression and hypocalcemia

This condition can cause neonatal seizures.

Question 22

What are the key lab findings in TRPM6 mutations?

Answer 22

• ↓Mg²⁺
• ↓Ca²⁺
• Normal urine Ca²⁺

Severe Mg²⁺ deficiency leads to neonatal seizures.

Question 23

What is the treatment for TRPM6 mutations?

Answer 23

Lifelong high-dose oral Mg²⁺ + IV for crises

This is necessary due to the severity of the condition.

Question 24

What disorder is associated with FXYD2 mutations?

Answer 24

Isolated Dominant Hypomagnesemia with Hypocalciuria

This disorder features a Na/K-ATPase γ-subunit defect.

Question 25

What is the mechanism of isolated dominant hypomagnesemia?

Answer 25

DCT Mg²⁺ wasting due to Na/K-ATPase γ-subunit defect ## Footnote Enhanced Ca²⁺ reabsorption in TALH leads to paradoxical hypocalciuria.

Question 26

List the clinical features of isolated dominant hypomagnesemia.

Answer 26

* Seizures * Chondrocalcinosis * ↓Mg²⁺ * ↓Urine Ca²⁺ ## Footnote Unlike Gitelman syndrome, this disorder does not present with hypokalemia or alkalosis.

Question 27

What disorder is associated with EGF mutations?

Answer 27

Isolated Recessive Hypomagnesemia (Normocalciuria) ## Footnote This disorder results from a pro-EGF defect.

Question 28

What are the key features of isolated recessive hypomagnesemia?

Answer 28

* Childhood seizures * Adult intellectual disability * Isolated ↓Mg²⁺ (normal Ca²⁺/K⁺) ## Footnote The condition is characterized by lack of calcium or potassium abnormalities.

Question 29

What disorder is associated with KCNJ10 mutations?

Answer 29

EAST/SeSAME Syndrome ## Footnote EAST stands for Epilepsy, Ataxia, Sensorineural deafness, Tubulopathy.

Question 30

What is the mechanism of EAST/SeSAME Syndrome?

Answer 30

Kir4.1 channel defect leading to DCT dysfunction ## Footnote This results in electrolyte imbalances and neurologic deficits.

Question 31

What are the lab findings in EAST syndrome?

Answer 31

* ↓Mg²⁺ * ↓K²⁺ * Metabolic alkalosis ## Footnote The lab findings can resemble those in Gitelman syndrome.

Question 32

What is the treatment for EAST syndrome?

Answer 32

Mg²⁺/K⁺ supplements, hearing aids ## Footnote Management focuses on addressing the deficiencies and associated hearing loss.

Question 33

What is the mechanism of hypocalcemia due to hypomagnesemia?

Answer 33

↓Mg²⁺ → impaired PTH secretion & skeletal resistance to PTH ## Footnote Correcting Mg²⁺ is essential as Ca²⁺ supplements will not be effective otherwise.

Question 34

What are the mechanisms of hypokalemia associated with hypomagnesemia?

Answer 34

* ↓Na/K-ATPase → K⁺ efflux from cells * ↓Mg²⁺ → loss of ROMK channel blockade → K⁺ wasting ## Footnote Hypokalemia can be refractory to treatment until Mg²⁺ is replenished.

Question 35

What mnemonic can be used to remember the top 5 disorders related to hypomagnesemia?

Answer 35

"CLD TRP FX EAST" ## Footnote This mnemonic helps recall the disorders associated with specific genetic defects.

Question 36

What is the key feature of FHHNC regarding urine calcium?

Answer 36

↑↑ urine Ca²⁺ ## Footnote This is a distinguishing feature of the disorder.

Question 37

What unique features are associated with TRPM6 mutations?

Answer 37

Neonatal seizures and hypocalcemia ## Footnote This disorder is characterized by impaired Mg²⁺ absorption.

Question 38

What distinguishes FXYD2 mutations from Gitelman syndrome?

Answer 38

Paradoxical hypocalciuria and no hypokalemia ## Footnote FXYD2 mutations lead to different clinical presentations.

Question 39

What is a key takeaway when dealing with refractory hypokalemia or hypocalcemia?

Answer 39

Always check Mg²⁺! ## Footnote Hypomagnesemia can significantly affect electrolyte balance.