Final answer:
Given the patient's presentation with itchy blisters, a biopsy showing IgA deposits, and other nonspecific symptoms, positive transglutaminase antibodies would likely be the next finding, indicating the presence of celiac disease and its associated dermatitis herpetiformis.
Step-by-step explanation:
The clinical presentation suggests the patient may have dermatitis herpetiformis (DH), which is a skin manifestation of celiac disease. This is supported by the symptoms of weakness, fatigue, palpitations, the appearance of itchy blisters on the elbows, and the histopathology findings from the skin biopsy showing neutrophilic infiltrate and IgA deposits. Moreover, the gastrointestinal symptoms often associated with celiac disease could be masked or absent.
The most probable subsequent workup finding for this patient would be positive transglutaminase antibodies. These antibodies are indicative of celiac disease and would correlate with the skin biopsy findings and the patient’s symptoms. A gluten-free diet is the primary treatment for DH and, consequently, would likely lead to the resolution of the skin lesions as well as the systemic symptoms of celiac disease.