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Zorluk: Çok zorSomatic Symptom and Eating Disorders

A 24-year-old woman is brought to the emergency department by her roommate due to profound muscle weakness and an inability to walk. The patient is a professional ballet dancer. The roommate reports that the patient has been highly distressed about her body image and frequently complains of "feeling huge," despite having a body mass index of 20.1 kg/m². The patient admits to occasional episodes where she consumes unusually large amounts of high-calorie foods in secret, followed by taking undisclosed over-the-counter medications to "flush it all out." She vehemently denies self-induced vomiting.

Vital signs show a blood pressure of 98/60 mmHg, a heart rate of 110/min, and a respiratory rate of 18/min. Physical examination reveals dry mucous membranes, delayed capillary refill, and symmetric 2/5 muscle strength in the bilateral lower extremities. There are no dental erosions or parotid gland swelling.

Initial laboratory studies show:
Sodium: 136 mEq/L
Potassium: 2.1 mEq/L
Chloride: 114 mEq/L
Bicarbonate: 12 mEq/L
Blood urea nitrogen: 34 mg/dL
Creatinine: 1.4 mg/dL

Arterial blood gas on room air reveals:
pH: 7.26
pCO2: 26 mmHg
pO2: 95 mmHg

Which of the following statements is most accurate regarding this patient's condition or appropriate management?

  1. Colonoscopy is likely to reveal a dark brown discoloration of the colonic mucosa with interspersed pale patches.Cevap
  2. B
    Arterial blood gas analysis indicates a primary metabolic acidosis with a superimposed respiratory acidosis.
  3. C
    Initiation of an antidepressant is contraindicated due to the risk of precipitating a manic episode.
  4. D
    The physician should notify the patient's employer regarding her condition to prevent imminent physical injury.
  5. E
    Evaluation will most likely reveal a profoundly low free thyroxine level with an inappropriately normal thyrotropin level.

Cevap

Colonoscopy is likely to reveal a dark brown discoloration of the colonic mucosa with interspersed pale patches.
The patient's presentation of binge eating and compensatory purging with a normal BMI is diagnostic of bulimia nervosa. However, unlike self-induced vomiting (which causes hypokalemic, hypochloremic metabolic alkalosis), this patient's labs show a normal anion gap metabolic acidosis (AG=136−(114+12)=10AG = 136 - (114 + 12) = 10) with severe hypokalemia. This specific pattern indicates lower gastrointestinal loss of potassium and bicarbonate, confirming the use of laxatives as her method of purging. Chronic use of anthraquinone laxatives (e.g., senna, cascara) causes melanosis coli, which appears on colonoscopy as a benign dark brown to black pigmentation of the colonic mucosa interspersed with pale patches of lymph follicles.

Adım Adım Çözüm

1
Diagnose the primary psychiatric disorder based on clinical history and BMI.
The patient engages in binge eating episodes followed by compensatory behavior (taking pills to "flush") while maintaining a normal BMI (20.1 kg/m²), which is diagnostic of bulimia nervosa.
Differentiating anorexia nervosa from bulimia nervosa relies heavily on BMI; patients with bulimia maintain a normal or overweight BMI (≥ 18.5 kg/m²).
2
Analyze the acid-base and electrolyte abnormalities to determine the specific purging method.
Labs show severe hypokalemia and a normal anion gap metabolic acidosis (AG=136−(114+12)=10AG = 136 - (114 + 12) = 10). This indicates lower gastrointestinal loss of potassium and bicarbonate.
Self-induced vomiting causes a hypokalemic, hypochloremic metabolic alkalosis (due to loss of gastric HCl). Conversely, laxative abuse causes a non-anion gap metabolic acidosis.
3
Evaluate the respiratory compensation using Winter's formula to rule out mixed acid-base disorders.
Expected pCO2=1.5×12+8=26pCO_2 = 1.5 \times 12 + 8 = 26 mmHg. The measured pCO2pCO_2 is exactly 26 mmHg, confirming an isolated, adequately compensated metabolic acidosis.
Ensuring there is no superimposed respiratory disorder confirms that the presentation is entirely explained by the laxative abuse.
4
Correlate the purging method with its expected long-term clinical findings.
Chronic abuse of stimulant laxatives (e.g., senna, cascara) leads to melanosis coli.
Melanosis coli is characterized endoscopically by a dark brown or black pigmentation of the colonic mucosa with pale patches of lymph follicles.

Anahtar Kavram

Patients with bulimia nervosa who purge via laxative abuse present with a normal anion gap metabolic acidosis and hypokalemia, contrasting with the metabolic alkalosis seen in vomiting. Chronic stimulant laxative abuse can lead to melanosis coli.
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Somatic Symptom and Eating Disorders

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