Guanfacinc Poisoning and Munchausen's Syndrome by Proxy

• Published in: Clinical toxicology (Philadelphia, Pa.) Pa.), 2008-06, Vol.46 (5), p.366-366
• Main Authors: Murphy, C M, Rickard, J W, Rose, SR, Cumpston, K L, Whitlow, K S
• Format: Article
• Language: English
• ISSN: 1556-3650

Objective: To describe the value of collaboration between clinicians and the toxicology laboratory when standard testing does not confirm a clinical diagnosis suspected from history and physical examination. Case report: A 4 y/o male with history of asthma and atypical absence seizures presented to an outside hospital after one day of intermittent lethargy. The child was evaluated for similar symptoms one-year prior, an extensive work-up was negative, and the child was placed on valproate for presumptive absence seizures and clonidine for insomnia. On examination at the outside hospital, the patient was somnolent but otherwise normal. Laboratory studies and an EEG were also normal. The patient was transferred to a tertiary care center and admitted to the pediatric neurology service. Extensive additional diagnostic testing was normal with the exception of an increased ammonia level (100 mg/dL) likely associated with valproate therapy. Clonidine and valproate were both discontinued, however the patient's somnolence persisted with periods of mild hypotension, bradycardia and miosis. A toxicology consultation (hospital day 4) identified a toxidrome consistent with the alpha-2 agonist properties of clonidine, but an analysis of urine using GC/MS was negative. Additional history revealed that the patient's sibling was prescribed guanfacine for ADHD, and hospital staff noticed an association between the mother's presence and the recurrence of the patient's symptoms. With this new development and the lack of a commercially available test, our clinical toxicology laboratory developed an assay that detected guan-facine in the patient's urine. Serial testing correlated positive guanfacine levels with recurring symptoms. This heightened suspicions of Munchausen's Syndrome by Proxy, however the mother denied complicity. During the subsequent Child Abuse Team investigation, the mother confessed to giving the patient guanfacine for over a year, including periods during this hospitalization. With parent-child interaction restricted, the patient fully recovered and was placed in foster care upon discharge. Conclusion: Munchausen's Syndrome by Proxy is a difficult diagnosis. In this case, guanfacine was administered to a child for over a year, resulting in unnecessary diagnostic testing and drug therapy. This case illustrates the value of combining clinical and analytical toxicologists' efforts in diagnosing occult poisoning.