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Zorluk: ZorNormal Pregnancy and Prenatal Care

A 31-year-old woman, gravida 2, para 1, at 28 weeks gestation, presents to the clinic for a routine prenatal visit. She reports feeling well and notes active fetal movement. Her only symptom is mild swelling of her ankles by the end of the day. Blood pressure is 112/68 mm Hg, and pulse is 84/min. Fundal height is 28 cm. Fetal heart rate is 145/min. Laboratory studies are obtained and the results are shown below:

Laboratory TestResult
Serum sodium134 mEq/L
Serum potassium4.1 mEq/L
Serum chloride103 mEq/L
Serum bicarbonate20 mEq/L
Blood urea nitrogen16 mg/dL
Serum creatinine1.2 mg/dL

Urinalysis shows trace protein, 1+ glucose, and is negative for leukocyte esterase and nitrites.

Which of the following findings in this patient is pathologic and requires further evaluation?

  1. A
    Serum sodium of 134 mEq/L
  2. B
    Serum bicarbonate of 20 mEq/L
  3. Serum creatinine of 1.2 mg/dLCevap
  4. D
    1+ glucosuria on urinalysis
  5. E
    Trace proteinuria on urinalysis

Cevap

The serum creatinine level of 1.2 mg/dL is pathologic, as normal pregnancy involves hyperfiltration that should lower serum creatinine below 0.8 mg/dL.
The correct finding that requires further evaluation is the serum creatinine of 1.2 mg/dL. During normal pregnancy, renal blood flow and glomerular filtration rate (GFR) increase by approximately 40% to 50% to assist in clearing maternal and fetal waste products. This physiologic hyperfiltration leads to increased clearance of creatinine and urea. Consequently, normal serum creatinine levels in pregnancy decrease to 0.4-0.8 mg/dL. A serum creatinine of 1.2 mg/dL, which might be considered reassuring in a non-pregnant individual, represents a significant reduction in GFR for a pregnant patient and strongly indicates underlying renal impairment that requires diagnostic workup.

Adım Adım Çözüm

1
Analyze the clinical presentation and context.
The patient is an asymptomatic pregnant woman at 28 weeks gestation presenting for a routine visit with a set of comprehensive lab values.
Establishing the baseline status helps differentiate between an acute illness and physiologic changes of pregnancy.
2
Evaluate the metabolic and electrolyte panel against pregnancy-specific reference ranges.
Sodium of 134 mEq/L and bicarbonate of 20 mEq/L represent normal dilutional hyponatremia and compensated respiratory alkalosis of pregnancy, respectively.
Pregnancy alters the body's osmostat and respiratory drive (via progesterone), resulting in new baseline normal values.
3
Assess the urinalysis findings.
Trace protein and 1+ glucose are observed.
The 50% increase in GFR during pregnancy increases the filtered load of glucose and proteins, commonly resulting in benign glucosuria and trace proteinuria.
4
Evaluate the renal function tests (BUN and Creatinine).
The BUN is 16 mg/dL and creatinine is 1.2 mg/dL. These values are abnormally elevated for a pregnant patient.
The physiologic increase in GFR should proportionately increase the clearance of urea and creatinine, normally dropping creatinine to 0.4-0.8 mg/dL. A level of 1.2 mg/dL signifies underlying renal dysfunction requiring workup.

Anahtar Kavram

Normal pregnancy induces a 50% increase in glomerular filtration rate (GFR), which causes a physiologic decrease in serum creatinine (normal range 0.4-0.8 mg/dL) and BUN. A creatinine level considered 'normal' for a non-pregnant patient indicates significant renal insufficiency during pregnancy.
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Normal Pregnancy and Prenatal Care

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