Interactive diabetes case 15: A 74-year-old patient with type 2 diabetes and recurrent hyperkalemia – A2

ANSWER — Correct.

You are correct to suspect the diagnosis of hyperglycemia-induced hyperkalemia in the setting of longstanding diabetes and impaired kidney function.

The immediate issue is to reduce the serum potassium level promptly. If the diagnosis is correct, then the potassium level should fall with administration of insulin and correction of the hyperglycemia. The administration of a short-acting insulin to reduce the glucose and the potassium levels over the next few hours is a reasonable short-term approach, together with an increase in the doses of the intermediate-acting insulin (NPH) to sustain this improvement. It is also necessary to address the dietary issues of a high carbohydrate diet and to reduce dietary potassium. The source of the high potassium in a patient's diet is not always evident immediately and requires a detailed review of the diet. It is important to provide the patient with specific instructions based on this review and written material about the content of potassium in various foods (table 1). Other modalities of treatment for a hyperkalemic emergency can be deferred because of the absence of electrocardiogram changes.

The following morning, the blood glucose level is 238 mg/dL (13.2 mmol/L) and the serum potassium level is 5.3 mEq/L. Over the ensuing weeks, you and your staff work with the patient to improve further her metabolic control by reviewing and reinforcing the dietary advice and making additional increases in the doses of insulin. You also advise the patient to take the second dose of NPH insulin at bedtime rather than before dinner. Her glucose values come into range on a regimen of NPH 48 units in the morning and 36 units at bedtime. The potassium returns to the mid 4 level. She returns to Italy.

The patient returns to see you one year later upon her return to the United States. She has fasting blood studies drawn the day before the scheduled office visit. The chemistry laboratory pages you because the potassium level is 6.6 mEq/L. The blood urea nitrogen (BUN) is 45 mg/dL, serum creatinine 1.7 mg/dL, blood glucose 194 mg/dL (10.8 mmol/L).

What do you do now?

●You await the patient's arrival for her scheduled appointment the following day, when you can repeat the serum potassium level to rule out hemolysis and get an electrocardiogram without alarming the patient. (See "Interactive diabetes case 15: A 74-year-old patient with type 2 diabetes and recurrent hyperkalemia – B1".)

●You call the patient and advise her to take 8 units of regular insulin and to adhere to her carbohydrate counting and the low potassium diet, based on your previous experience with this patient. You plan to repeat the serum potassium level at the time of the office visit the following day. (See "Interactive diabetes case 15: A 74-year-old patient with type 2 diabetes and recurrent hyperkalemia – B2".)

●You call the patient and advise her to go to the nearest emergency department immediately. You speak also with her daughter and repeat the instructions. The patient and her daughter agree to do as advised. (See "Interactive diabetes case 15: A 74-year-old patient with type 2 diabetes and recurrent hyperkalemia – B3".)