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Clinician’s Corner: Deficiency of Potassium and Calcium

This week we will explore the common causes of deficiency of potassium and calcium.


The kidney is the major player in potassium regulation, regulating about 90% of excretion. Potassium  balance is maintained by adjusting secretion into the urine in response to dietary intake. Low levels of potassium can result in muscle weakness, adverse effects on the kidneys and cardiac arrhythmias.

Drugs that Lower Potassium Levels

Thiazide Diuretics (Hydrochlorothiazide) Work in the kidney.  Doses over 25 mg are not any more effective.
Loop Diuretics

Furosemide, Torsemide, Bumetanide

20 mEq potassium per day is usually needed to keep from being potassium deficient if taking diuretics (“water pills”)
Antipsychotic drugs

(Risperidone and quetiapine)

Can be a concern in the elderly
Carbonic Anhydrase Inhibitors

Acetazolamide (Diamox)

Mild diuretic works in the kidney. A weak diuretic most commonly used for glaucoma and altitude sickness.
Excessive sweating, vomiting and diarrhea. Colon cleansing. Contribute potassium loss.



Serum calcium is regulated by parathyroid hormone (PTH) and vitamin D. These hormones effect the bone, kidney, and the gastrointestinal tract. Parathyroid hormone decreases calcium excretion in the kidney, increases absorption of calcium in the gut, and increases bone resorption.

Drugs that lower calcium levels


(Alendronate (Fosamax®), Risedronate (Actonel®), Ibandronate (Boniva®) etc)

Block  breakdown  of bone
Calcitonin (Miacalcin®) Block osteoclast re-absorption of bone
Cinacalcet (Sensipar®) Lowers serum calcium (binds to receptors on parathyroid gland)
Phenytoin (Dilantin®) (and other inducers of Vitamin-D) Phenytoin,  speeds up breakdown of Vitamin-D
Vitamin-D deficiency Blocks absorption of calcium from gut
Corticosteroids Increase kidney calcium excretion and decrease gastrointestinal calcium absorption, resulting in lower calcium levels
Excess phosphate levels (seen in chronic kidney disease) May lead to decrease calcium absorption from the gut.
Low magnesium levels (most commonly due to alcoholism, malabsorption, and diuretic therapy) magnesium depletion can cause hypocalcemia by producing parathyroid hormone (PTH) resistance,

Your Thompson pharmacist can guide you on appropriate use of these two very important nutrients.  All potassium prescriptions require a prescription.  Calcium supplements are available without a prescription, and depending on your other medications you take, one form of calcium may be more appropriate.

Got a question? Ask your Thompson pharmacist… At Thompson Pharmacy… its all for YOU.