Hyponatremia is a condition that occurs when the sodium level in the blood is too low. This is due to excessive retention of water by the body. This excess water dilutes the blood sodium and causes low sodium levels. This can be caused by multiple conditions including volume depletion, hormonal abnormalities, lung disease and neurologic disease. The symptoms can range from negligible to life threatening depending on degree and include nausea, headaches, confusion, fatigue,  and seizures.  Hospitalization may be required if the sodium level reduction is extreme. Treatment includes a range of options including fluid restriction, increased sodium intake, and medications.

Hypernatremia is a high blood sodium level due to inadequate blood water relative to sodium.  Causes for this could be medications including diuretics, decreased thirst, poor oral intake, and neurologic conditions. Treatment is aimed at repleting the water in the blood.

All sodium disorders require skill in diagnosis and treatment.  Overly rapid correction can be harmful.

Hypokalemia is low potassium level in the blood. This is often caused by medications such as diuretics and laxatives, low magnesium,  diarrhea, or insufficient intake of dietary potassium.   Symptoms of hypokalemia include constipation, palpitations, fatigue, muscle weakness, and tingling or numbness. Low potassium can affect the heart rhythm, and when it is very low can result in cardiac arrhythmias.

Hyperkalemia is often seen in chronic kidney disease and can be related to medication use and certain hormonal disorders.  Pumping or squeezing the fist during the blood drawing process can cause an artefactual increase in blood potassium levels. Symptoms of hyperkalemia include muscle fatigue, weakness and cardiac arrhythmias.  It can be controlled with dietary modifications, medications, and dialysis.  When severe, hospitalization is required as very high values can cause life threatening cardiac abnormalities.  Foods that are high in potassium include citrus fruit, bananas, potatoes, tomatoes, and melons.  

 Abnormal blood magnesium levels can effect the heart, muscles and nervous system.  Disorders of blood magnesium can be caused by inadequate nutritional intake, alcohol use, vomiting, diarrhea, diabetes mellitus, diuretics, intestinal malabsorption syndromes,  and inflammatory bowel disease with chronic diarrhea.  Oral and intravenous magnesium repletion or a combination of the two is indicated for a low magnesium level.  

Hypercalcemia (high blood calcium) is a common clinical problem.  It is often caused by overactive production of parathyroid hormone by the parathyroid gland.  This condition is known as primary hyperparathyroidism.  Hypercalcemia can cause kidney stones, fatigue, weakness, depression,  memory impairment, and bone disease.  If symptomatic, surgery on the parathyroid gland may be necessary. Sometimes, in mild asymptomatic cases the calcium level and symptoms are simply monitored.  Other causes of hypercalcemia include malignancy, vitamin D intoxication, and medications.