Calcium and Magnesium Imbalance

Definition/Etiology:

• Hypocalcemia
• Serum calcium levels below 8.8
• Hypercalcemia
• Serum calcium above 10.2
• Hypermagnesemia
• Serum level above 2.2
• Hypomagnesemia
• Serum level below 1.7

Pathophysiology:

• Hypercalcemia – The principal pathophysiologic alteration in severe hypercalcemia accompanying hyperparathyroidism and malignancy is enhanced osteoclastic bone resorption. Hypercalcemia impairs renal mechanisms that lead to sodium and calcium excretion; PTH and PTHrP acting on renal tubules enhance further calcium reabsorption.

• Hypocalcemia – Hypocalcemia results whenever there is a net efflux of calcium from the extracellular fluid in greater quantities than the intestines or bones can replace. Symptoms are primarily neurological, with the inadequate calcium levels causing hyperexcitability of neuronal membranes.

• Hypermagnesium- The pathophysiology of hypermagnesemia related to excess laxative use is different. In this case, the huge amount of magnesium given through the digestive tract can lead to overwhelming the excretory mechanism, especially in cases with underlying subclinical renal failure

• Hypomagnesemia is an electrolyte disturbance caused when there is a low level of serum magnesium (less than 1.46 mg/dL) in the blood. Hypomagnesemia can be attributed to chronic disease, alcohol use disorder, gastrointestinal losses, renal losses, and other conditions.

Clinical Presentation:

Hypercalcemia:

• Frequent urination and thirst
• Fatigue
• Bone pain
• HA, N/V/D
• Constipation
• Forgetfulness, depression, anxiety
• Muscle aches, cramping, twitches
• flank or thigh pain and polyuria and constipation. Flank and thigh pain secondary to renal calculi. Polyuria from the inhibition of ADH by calcium in the distal tubules.

Hypocalcemia:

• Muscle cramps
• Dry scaly skin, brittle nails
• Confusion, memory problems, irritability, restlessness, depression, hallucinations.
• Circumoral parasthesias
•  Bleeding abnormalities because calcium assists in th converting prothrombin to thrombin in the coagulation cascade.
• Bronchospasm can lead to laryngeal stridor and seizures secondary to neuromuscular irritability.

Hypermagnesemia:

Non-specific bone pain, anorexia, lethargy, headache, confusion.

Hypomagnesemia:

• Tremors
• Tetany
• fatigue
• back pain.

Collaborative Management:

• Get an EKG STAT
• EKG – prolonged QT with Hypo C – leads to torsades
• Increased calcium predisposes pt to repolarization changes (shortened QT) which can lead to cardiac arrest. Hypercalcemia can enhance digitalis effect. 
• In assessing for hypocalcemia, one of the things we can use is Chvostek’s Sign. This entails tapping a finger on the skin above the supramandibular portion of the parotid gland and observing for twitching of the upper lip on the same side as the stimulation. 
• Treat with NS to increase calcium excretion, Loop diuretics prevent tubular reabsorption of calcium

Evaluation | Patient Monitoring | Education:

• Symptom reduction?
• Serial labs for return to baseline. 
• Continued cardiac monitoring
• Education based on underlying cause of imbalance

Linchpins: (Key Points)

• Labs labs labs
• Heart guard