Case Report: Treatment of Delirium Induced by Severe Lead Poisoning Using Permissive Hypercalcemia

Friday, November 11, 2022

11:00 AM – 12:30 PM

Location: Room 217

Presenting Author(s)

Mackenzie Sowers (she/her/hers)

Medical Student
The University of Alabama at Birmingham
Birmingham, Alabama

PDF

Co-Author(s)

Dwight Kemp, MD, MS

Resident
The University of Alabama at Birmingham
Birmingham, Alabama
J. Reid Black, MD

Resident
The University of Alabama at Birmingham
Birmingham, Alabama
Paulo Marcelo Gondim Sales, MD, MS

Psychiatrist
River Region Psychiatry Associates
Birmingham, Alabama

Abstract:

Background:

Lead poisoning remains a public health concern despite fewer diagnoses each year (CDC, 2013). Even with the emergence of neuropsychiatric symptoms with chronic blood lead levels (BLL) as low as 5 mcg/dL (Rocha, 2019), there is a dearth of literature regarding the treatment of neuropsychiatric symptoms of lead poisoning, and guidelines for acute management are limited to chelation therapy and supportive measures.

Physiologically, lead acts as an unregulated competitor of calcium, thus inhibiting or activating calcium-dependent processes (Bridges, 2005). This report describes a patient with acute on chronic lead poisoning and new-onset neuropsychiatric symptoms who was successfully treated using permissive hypercalcemia (defined as borderline elevated levels of ionized calcium) alongside psychotropics.

Case:

A 22-year-old hospitalized woman without medical or psychiatric history was found to have a BLL of 85mcg/dL on extended workup for encephalopathy, which prompted the use of chelation therapy and intensive care management. Consultation-liaison psychiatry was consulted on hospital day 24 management of refractory delirium and anxiety despite optimized care. On evaluation, the patient displayed paratonias, tremors, distractibility, disorientation, executive dysfunction, auditory/visual hallucinations, paranoia, depressive symptoms, and unspecific anxiety. On review of systems, she reported perioral/acral paresthesias and myalgias concerning for hypocalcemia despite normal ionized calcium levels. After 6 days of treatment with permissive hypercalcemia concomitant with olanzapine, clonazepam, and fluoxetine, the patient demonstrated significant improvement in her Montreal Cognitive Assessment (MoCA) (from 4/30 to 26/30), Hospital Anxiety and Depression Scale (HADS) depression and anxiety scores (From 14+18 to 4+13, respectively), as well as complete resolution of delirium.

Discussion:

A patient with severe lead poisoning and associated neuropsychiatric symptoms displayed a rapid, profound response to permissive hypercalcemia and psychotropics. We postulate that elevated levels of calcium may overcome lead-induced competitive inhibitory effects on calcium-dependent processes in the central nervous system (CNS), thereby improving a case of severe lead toxicity that presented as a phenocopy of hypocalcemia-induced neuropsychiatric symptoms despite having normal range calcium levels. Our findings suggest that dysfunctional calcium dynamics may play a significant role in the pathophysiology of neuropsychiatric symptoms observed in severe lead poisoning in adults.

Conclusion:

Physicians may consider permissive hypercalcemia alongside psychotropics when treating neuropsychiatric symptoms of patients suffering from severe lead poisoning, as it is a relatively innocuous treatment that may lead to significant clinical improvement.

References:

1. Centers for Disease Control and Prevention (CDC). Very high blood lead levels among adults - United States, 2002-2011. MMWR Morb Mortal Wkly Rep 2013; 62:967.

2. Rocha A, Trujillo KA. Neurotoxicity of low-level lead exposure: History, mechanisms of action, and behavioral effects in humans and preclinical models. Neurotoxicology. 2019 Jul;73:58-80.

3. Bridges CC, Zalups RK. Molecular and ionic mimicry and the transport of toxic metals. Toxicol Appl Pharmacol. 2005 May 1;204(3):274-308.