WBR1090

Author	[[PageAuthor::Mohamed Moubarak, M.D. [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Emergency Room
Sub Category	SubCategory::Cardiovascular, SubCategory::Electrolytes
Prompt	[[Prompt::A 65-year-old male comes to emergency department complaining of chest pain, sweating, and fatigue. He is a newly diagnosed lung cancer patient, and undergoes his first round of cisplatin. He has insignificant past medical history. On examination, his BP is 90/60 mmHg, irregular heart rate 50 beat per minute, temperature 37 C (98.6 F), respiratory rate is 19/minute. His laboratory tests are: Sodium 135 Potassium 7.6 Chloride 108 CO2 20 BUN 35 Creatinine 3.4 Glucose 152 Calcium 7.5 Which of the following is the best urgent step in the management of this patient?]]
Answer A	AnswerA::IV atropine
Answer A Explanation	[[AnswerAExp::Incorrect IV atropine does not stabilize the myocardium from the effects of hyperkalemia.]]
Answer B	AnswerB::IV calcium gluconate
Answer B Explanation	[[AnswerBExp::Correct Calcium gluconate is necessary to help stabilize the myocardium from the effects of hyperkalemia]]
Answer C	AnswerC::Oral kayexalate
Answer C Explanation	[[AnswerCExp::Incorrect Kayexalate binds potassium in the large intestine and helps remove total body potassium; however, this is not immediately helpful in treating life-threatening hyperkalemia because of the increased time to onset of action.]]
Answer D	AnswerD::Subcutaneous insulin
Answer D Explanation	[[AnswerDExp::Incorrect Insulin is given in conjunction with dextrose, as the first-line treatment for hyperkalemia. It will promote the movement of potassium intracellularly, but will not protect the myocardium from the effect of hyperkalemia.]]
Answer E	AnswerE::IV glucagon
Answer E Explanation	[[AnswerEExp::Incorrect IV glucagon does not stabilize the myocardium from the effects of hyperkalemia.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient has tumor lysis syndrome. The destruction of malignant cells by chemotherapeutic agents will lead to the release of intracellular contents, including potassium, phosphorus, and uric acid (from nucleic acids). This can result in hyperkalemia, hyperuricemia, and hyperphosphatemia. This patient is having hemodynamic instability because of life-threatening hyperkalemia. Calcium gluconate, in this case, is necessary to help stabilize the myocardium from the effects of hyperkalemia, although it will not have an effect on the serum potassium itself. Intravenous insulin, given in conjunction with dextrose (in order to prevent hypoglycemia), is the first-line treatment for hyperkalemia, as it will promote the movement of potassium intracellularly. Albuterol is also effective in the treatment of hyperkalemia, as a beta agonist will promote the cellular uptake of potassium. Kayexalate binds potassium in the large intestine and helps remove total body potassium; however, this is not immediately helpful in treating life-threatening hyperkalemia because of the increased time to onset of action. Educational Objective: Calcium gluconate is necessary to help stabilize the myocardium from the effects of hyperkalemia. References: http://www.wikidoc.org/index.php/Tumor_lysis_syndrome]]
Approved	Approved::No
Keyword	[[WBRKeyword::Tumor lysis syndrome]]
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::