Elevated alkaline phosphatase: The initial laboratory abnormality in an atypical presentation of Takayasu Arteritis

Background: Takayasu Arteritis rarely presents in men over the age of 40, particularly with an isolated elevated alkaline phosphatase level. Case presentation: A 46-year-old Hispanic man with no prior history of rheumatic disease presented with acute onset of chest pain radiating to his left upper extremity. His cardiovascular workup was unremarkable with exception of an elevated alkaline phosphatase level (ALP), approximately three times the upper limit of normal. Over a short period of time, his ALP up trended and clinical exam revealed BP discrepancies between his upper extremities, vascular bruits and a profound asymmetry in brachial and radial pulses. MRA-Chest confirmed mural thickening and luminal narrowing of the proximal left subclavian artery and the diagnosis of Takayasu Arteritis was made. Upon receiving glucocorticoids and corticosteroid sparing immunosuppressive agents, his clinical manifestations (chest pain, left arm claudication) had markedly improved while ALP decreased. Conclusion: In addition to clinical exam and imaging studies, laboratory studies (such as ALP) may aid in support of a diagnosis of large vessel vasculitis. In the literature, this has been described primarily in those with giant cell arteritis/polymyalgia rheumatica. In patients with an elevated ALP in the appropriate clinical setting, consideration should be given to the diagnosis of Takayasu Arteritis. This may aid in early initiation of appropriate therapy.