Anorexia nervosa laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Joseph Nasr, M.D.[2]
Overview
Laboratory evaluation in anorexia nervosa is used to assess the medical consequences of starvation, identify complications related to purging behaviors, and monitor physiologic stability over time. Laboratory results may be normal early in the illness and do not reliably reflect disease severity; therefore, normal findings do not exclude significant medical risk.[1][2][3][4]
Core Laboratory Tests and Expected Findings
Serum Proteins and Nutritional Markers
- Albumin
- Often normal until late stages of illness
- May be low in severe malnutrition, inflammation, or advanced disease[1]
- Total protein
- May be reduced with prolonged protein-energy malnutrition
Albumin and total protein are poor screening tools for anorexia nervosa but are useful for longitudinal monitoring.[1]
Hematologic Studies
- Complete blood count (CBC) may reveal:
- Normocytic, normochromic anemia
- Leukopenia, particularly neutropenia
- Thrombocytopenia in severe cases[1]
These findings reflect bone marrow suppression secondary to starvation and are typically reversible with nutritional rehabilitation.
Electrolytes and Metabolic Panel
- Electrolytes
- Kidney function tests
- Elevated blood urea nitrogen (BUN) due to dehydration
- Creatinine may be deceptively low due to reduced muscle mass[1]
Electrolyte abnormalities increase the risk of cardiac arrhythmias and neurologic complications.
Liver Function Tests
- Elevated transaminases (AST, ALT) may occur due to:
- Starvation-related hepatocellular injury
- Rapid refeeding[1]
- Alkaline phosphatase may be low in malnutrition
Thyroid Function Tests
- Euthyroid sick syndrome is common:
- Low triiodothyronine (T3)
- Normal or low thyroxine (T4)
- Normal or low thyroid-stimulating hormone (TSH)[1]
These changes reflect adaptive metabolic suppression, not primary thyroid disease.
Urinalysis
May show:
- High specific gravity due to dehydration
- Ketonuria in states of prolonged starvation
- Electrolyte abnormalities if purging behaviors are present[1]
Cardiovascular and Bone Health–Related Tests
Electrocardiogram (ECG)
- Sinus bradycardia
- Prolonged QT interval
- Possible arrhythmias in the setting of electrolyte abnormalities[1][2]
ECG abnormalities are a key indicator of medical instability.
Bone Density Assessment
- Dual-energy x-ray absorptiometry (DEXA) may demonstrate:
Bone loss may be partially irreversible, especially with delayed treatment.
Summary
Laboratory findings in anorexia nervosa reflect the systemic effects of chronic undernutrition and may involve electrolyte disturbances, hematologic suppression, endocrine adaptation, and organ dysfunction. Laboratory testing is essential for monitoring complications and guiding clinical decision-making, but results may underestimate disease severity.
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 SøebyM, Gribsholt SB, Clausen L, Richelsen B. Fracture risk in patients with anorexia nervosa over a 40-year period. J Bone Miner Res. 2023;38(11): 1586-1593. doi:10.1002/jbmr.4901
- ↑ 2.0 2.1 2.2 American Psychiatric Association. Practice Guideline for the Treatment of Patients With Eating Disorders. 4th ed. American Psychiatric Association Publishing; 2023.
- ↑ Hornberger LL, Lane MA; Committee on Adolescence. Identification and management of eating disorders in children and adolescents. Pediatrics. 2021;147(1):e2020040279. doi:10.1542/ peds.2020-040279
- ↑ Society for Adolescent Health and Medicine. Medical management of restrictive eating disorders in adolescents and young adults. J Adolesc Health. 2022;71(5):648-654. doi:10.1016/j.jadohealth.2022. 08.006
- ↑ Nitsch A, Dlugosz H, Gibson D, Mehler PS. Medical complications of bulimia nervosa. Cleve Clin J Med. 2021;88(6):333-343. doi:10.3949/ccjm.88a. 20168