A 7-day-old male infant presents to the pediatrician for weight loss. There is no history of excessive crying, irritability, lethargy, or feeding difficulty. The parents deny any history of fast breathing, bluish discoloration of lips/nails, fever, vomiting, diarrhea, or seizures. He was born at full term by vaginal delivery without any perinatal complications and his birth weight was 3.6 kg (8 lb). Since birth he has been exclusively breastfed and passes urine six to eight times a day. His physical examination, including vital signs, is completely normal. His weight is 3.3 kg (7.3 lb); length and head circumference are normal for his age and sex. Which of the following is the next best step in the management of the infant?
AReassurance of parents
BEvaluation of the mother for malnutrition
CAdmission of the infant in the NICU to treat with empiric intravenous antibiotics
DEmphasize the need to clothe the infant warmly to prevent hypothermia
ESupplementation of breastfeeding with an appropriate infant formula
A physician at an internal medicine ward notices that several of his patients have hyponatremia without any associated symptoms. Severe hyponatremia, often defined as < 120 mEq/L, is associated with altered mental status, coma, and seizures, and warrants treatment with hypertonic saline. Because some patients are chronically hyponatremic, with serum levels < 120 mEq/L, but remain asymptomatic, the physician is considering decreasing the cutoff for severe hyponatremia to < 115 mEq/L. Changing the cutoff to < 115 mEq/L would affect the validity of serum sodium in predicting severe hyponatremia requiring hypertonic saline in which of the following ways?
AIncreased sensitivity and decreased positive predictive value
BIncreased specificity and decreased positive predictive value
CDecreased specificity and increased negative predictive value
DIncreased specificity and decreased negative predictive value
EDecreased sensitivity and decreased positive predictive value
A 23-year-old man presents to the emergency department for altered mental status after a finishing a marathon. He has a past medical history of obesity and anxiety and is not currently taking any medications. His temperature is 104°F (40°C), blood pressure is 147/88 mmHg, pulse is 200/min, respirations are 33/min, and oxygen saturation is 99% on room air. Physical exam reveals dry mucous membranes, hot flushed skin, and inappropriate responses to the physician's questions. Laboratory values are ordered as seen below. Hemoglobin: 15 g/dL Hematocrit: 44% Leukocyte count: 8,500/mm^3 with normal differential Platelet count: 199,000/mm^3 Serum: Na+: 165 mEq/L Cl-: 100 mEq/L K+: 4.0 mEq/L HCO3-: 22 mEq/L BUN: 30 mg/dL Glucose: 133 mg/dL Creatinine: 1.5 mg/dL Ca2+: 10.2 mg/dL AST: 12 U/L ALT: 10 U/L Which of the following is the best next step in management?
ALactated ringer
BHypotonic saline
C50% normal saline 50% dextrose
DNormal saline
EDextrose solution
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