Laboratory Studies

With urine chromatography,^{[3, 22, 23, 26, 29]}increased levels of neutral amino acids (eg, glutamine, valine, phenylalanine, leucine, asparagine, citrulline, isoleucine, threonine, alanine, serine, histidine, tyrosine, tryptophan) and indican are found in the urine. Urinary indoxyl derivatives (ie, 5-hydroxyindoleacetic acid) may be demonstrated following an oral tryptophan load. Urine excretion of proline, hydroxyproline, and arginine remains normal, which differentiates Hartnup disease from other causes of gross aminoaciduria. Perform urine chromatography to exclude nutritional pellagra.

Plasma concentrations of amino acids are usually normal.^{[3, 22, 23, 26, 29]}

Procedures

Jejunal biopsy may be required in selected patients (transport defect may be identified in vitro). Skin biopsy may be required in selected patients.^{[23, 25, 26, 27]}

Histologic Findings

Changes in the skin are similar to those seen in pellagra. Findings are not diagnostic and include hyperkeratosis, parakeratosis, epidermal atrophy, hyperpigmentation of the basal layer, and a mild superficial dermal lymphocytic infiltrate. Bullae may be either intraepidermal or subepidermal. Hyperplasia of the sebaceous glands with follicular dilatation and plugging may occur.^{[25, 26, 27]}

Treatment & Management

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Media Gallery

Photosensitivity with erythema, desquamation, and hypopigmentation and hyperpigmentation on the face.
Erythema and desquamation on the sun-exposed area of the right arm.

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Author

Lidija Kandolf Sekulovic, MD, PhD Professor, Head of the Department of Dermatology and Venereology, Medical Faculty, Military Medical Academy, Belgrade, Serbia

Lidija Kandolf Sekulovic, MD, PhD is a member of the following medical societies: American Society of Clinical Oncology, European Academy of Dermatology and Venereology, European Society for Medical Oncology, Serbian Association of Dermatorvenerologists

Disclosure: Nothing to disclose.

Coauthor(s)

Djordjije Karadaglic, MD, DSc Professor, School of Medicine, University of Podgorica, Podgorica, Montenegro

Djordjije Karadaglic, MD, DSc is a member of the following medical societies: American Academy of Dermatology, European Academy of Dermatology and Venereology, Serbian Association of Dermatorvenerologists

Disclosure: Nothing to disclose.

Ljubomir Stojanov, MD, PhD Lecturer in Metabolism and Clinical Genetics, University of Belgrade School of Medicine, Serbia

Disclosure: Nothing to disclose.

Specialty Editor Board

David F Butler, MD Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, Association of Military Dermatologists, Phi Beta Kappa, Texas Dermatological Society

Disclosure: Nothing to disclose.

Robert A Schwartz, MD, MPH Professor and Head of Dermatology, Professor of Pathology, Professor of Pediatrics, Professor of Medicine, Rutgers New Jersey Medical School

Robert A Schwartz, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, New York Academy of Medicine, Royal College of Physicians of Edinburgh, Sigma Xi, The Scientific Research Honor Society

Disclosure: Nothing to disclose.

Chief Editor

William D James, MD Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine

William D James, MD is a member of the following medical societies: American Academy of Dermatology, Society for Investigative Dermatology

Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD<br/>Served as a speaker for various universities, dermatology societies, and dermatology departments.

Acknowledgements

Mark A Crowe, MD Assistant Clinical Instructor, Department of Medicine, Division of Dermatology, University of Washington School of Medicine

Mark A Crowe, MD is a member of the following medical societies: American Academy of Dermatology and North American Clinical Dermatologic Society

Disclosure: Nothing to disclose.