WBR1125

Author	[[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Inpatient Facilities
Sub Category	SubCategory::Electrolytes
Prompt	[[Prompt::A 55 year old male who underwent gastric bypass surgery 2 days prior to carcinoma head of pancreas experiences generalized tonic clonic seizures. Postoperatively, the patient was managed with opiods for pain at the surgical site and with IV fluids to hold blood pressure above 110/70 mmHg. On examination the patient is lethargic and his vitals are temperature 37 degree Celsius, pulse: 106/min, blood pressure 120/70 mmHg and respirations: 16/min. His pulse oximetry reading is 94 % in room air. Electrolyte panel results are as follows: Serum Na: 112 mEq/L Serum K: 4 mEq/L Chloride: 94 mEq/L Bicarbonate: 24 mEq/L BUN: 24 mg/dl Serum creatinine: 1.2 mg/dl Calcium: 9 mg/dl Blood glucose: 130 mg/dl What is the most appropriate next step in the management of this patient?]]
Answer A	AnswerA::Ringer lactate
Answer A Explanation	AnswerAExp::Ringer lactate is not used in the management of hyponatremia.
Answer B	AnswerB::3 % sodium chloride
Answer B Explanation	[[AnswerBExp::In patients with severe hyponatremic symptoms and in symptomatic patients with underlying intracranial disease, the serum sodium must initially be raised quickly to prevent possibly irreversible neurologic injury. This patient has an ongoing seizures with plasma sodium concentration <115 meq/L, and hence correction can be attempted at up to 2 meq/L/hr using 3 % sodium chloride solution.]]
Answer C	AnswerC::Water restriction
Answer C Explanation	[[AnswerCExp::Patients with euvolemic hyponatremia and less severe symptoms of can be treated with less aggressive therapy, such as fluid restriction and oral salt tablets.]]
Answer D	AnswerD::0.45 % normal saline
Answer D Explanation	AnswerDExp::Hypervolemic hyponatremia should be treated by treating the underlying cause and intravenous administration of 0.45% normal saline can be used in rare cases.
Answer E	AnswerE::0.9 % normal saline
Answer E Explanation	AnswerEExp::In the setting of hypovolemic hyponatremia, intravenous administration of 0.9% normal saline may be effective.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The electrolyte disturbance, hyponatremia is defined when sodium concentration in the plasma falls below 130 mmol/L. Hyponatremia is due to an excess of free water in the body, not due to a deficiency of sodium. The treatment of hyponatremia will depend on the underlying cause and whether the patient's volume status is hypervolemic, euvolemic, or hypovolemic. In the setting of hypovolemia, intravenous administration of normal saline may be effective, but caution must be exercised not to raise the serum sodium level too quickly in order to lessen the chance of the development of central pontine myelinolysis (CPM), a severe neurological disease. Euvolemic hyponatremia is usually managed by fluid restriction and treatment to abolish any stimuli for ADH secretion such as nausea. Likewise, drugs causing SIADH should be discontinued if possible. Patients with euvolemic hyponatremia that persists despite those measures may be candidates for a so-called vaptan drugs. Hypervolemic hyponatremia should be treated by treating the underlying cause (e.g. heart failure, cirrhosis). In practice, it may not be possible to do so, in which case the treatment of the hyponatremia becomes the same as that for euvolemic hyponatremia (i.e. fluid restriction and/or use of a vaptan drug). The rate of correction of hyponatremia should be 0.5-1.0meq/L/hr, with not more than a 12 meq/l correction in 24 hrs. If the patient has ongoing seizures (or [Na+]<115 meq/L), correction can be attempted at up to 2 meq/L/hr, but only while seizure activity lasts and the [Na+] exceeds 125-130 meq/L. Educational Objective: Serum sodium must initially be raised quickly to prevent irreversible neurologic injury in cases of severe symptomatic hyponatremia. References: ]]
Approved	Approved::Yes
Keyword	[[WBRKeyword::Hyponatremia]]
Linked Question	Linked::
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