Originally Published: Modern Resident, Dec/Jan 2011
Original Author: Cameron McLaughlin, OMS IV Arizona College of Osteopathic Medicine
Submitted by: Rachel Engle, DO, COmmunication Committee Chair
Recently, I saw a patient in the ED who was hyperkalemic and
hypoglycemic. The patient was in acute renal failure secondary
to
Bactrim (TMP-SMX) use for cellulitis. During the first 24 hours of her
stay in the hospital, she continued to experience episodes of
hypoglycemia. In cases like this, it is important to remember the
underlying physiology of renal failure before automatically treating
hyperkalemia with standard protocols. (Standard treatment is "C BIG KA,"
or calcium, bicarbonate, insulin with glucose, kayexalate and
albuterol).
Why? Sure, insulin is one of the early treatments for hyperkalemia,
and usually we give it with some glucose. However, it is important to
remember that the kidneys are a major site of insulin clearance from the
body. In acute kidney injury, the glomerular filtration rate is assumed
to be less than 10 mL/min, so not only is potassium clearance reduced
(leading to hyperkalemia), but the insulin clearance is greatly reduced,
too. This leads to insulin retention, and, even in an obese, diabetic
female, can cause severe hypoglycemia. Most protocols for hyperkalemia
call for 1 amp of D50 along with the standard 10 units of insulin, but
patients in severe renal failure may need significantly more glucose if
they continue to retain insulin. Be aware of the physiology of
hypoglycemia in renal failure, order frequent blood glucose monitoring,
and give additional glucose as needed
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