Case Presentation: Pauci-immune Glomerulonephritis and Autoimmune Hypothyroidism
Background: Our patient is a 51 year-old woman who presented to the emergency department due to new low back pain and hematuria in the setting of worsening fatigue and exercise tolerance over the past few months. Additional concerns include metomenorrhagia for a few years. She has lost 20 pounds over the past 2 months, although she notes changing her diet to try to lose weight. She has been feeling very fatigued. No fevers, chills, recent pharyngitis, sick contacts, or travel. Purpose: Examine the known relationship between these conditions. Materials and Methods: PubMed search of literature using MeSH subject headings. Discussion: This patient presented with symptoms characteristic of both kidney disease and hypothyroidism, and her diagnoses were confirmed by laboratory results. The simultaneous presentation with pauci-immune pANCA glomerulonephritis and autoimmune hypothyroidism raises the question of whether these are linked or merely coincidental. Pauci-immune glomerulonephritis occurs 3.1 cases/million/year in the US. The rates are higher for caucasians, males, and age greater than 65 years (Lionaki and Boletis). Autoimmune thyroid dysfunction is the most common cause of hypothyroidism in areas not iodine deficient, and occurs at about a rate of 1-2% of the population, more common in women and with increasing age (Vanderpump). This patient being female, Caucasian, and in her 50s was at an increased risk for hypothyroidism. Chronic kidney disease is commonly associated with hypothyroidism, with either primary disorder able to lead to the other (Iglesias et el). Notably, however, the kidney impairment caused by hypothyroidism is generally reversible with treatment (Iglesias et al). Interestingly, a recent European study found that among patients with CKD, subclinical hyperthyroidism raised the risk of disease progression compared to subclinical hypothyroidism (Chaker et al). Granulomatosis with polyangiitis with elevated thyroid peroxidase antibody has been reported 5 times in the literature (Rosmarakis et al). There is an additional report of subacute thyroiditis preceding GPA (Mukae). A cohort of 180 patients with granulomatosis with polyangiitis found significantly higher rates of pre-existing thyroid dysfunction among those with severe kidney disease (Stone et al). Proposed mechanisms include common damage due to immune deposits or sharing an underlying autoimmune predisposition (Iglesias et al). Conclusion: Although the biological mechanism of the overlap between pauci-immune glomerulonephritis and autoimmune hypothyroidism requires additional research, the clinical overlap has been demonstrated to be more than random.