When the rules break down: how nephrologists navigate diagnostic complexity in real-world practice

Diagnostic reasoning in nephrology requires clinicians to navigate between competing heuristics: Occam's razor, which favours a single unifying diagnosis, and Hickam's dictum, which recognises that patients may harbour multiple simultaneous conditions. In a specialty defined by systemic complexity, the conditions under which nephrologists shift between these frameworks, and the structural forces that shape those shifts, are not well understood. This study investigated how nephrologists develop and deploy diagnostic heuristics across three intersecting domains: medical training, individual clinical experience, and system-level constraints.

Semi-structured interviews were conducted with nine nephrologists across Canada and analysed using an inductive narrative approach.

Three interlocking themes emerged. First, clinical decision-making is typically acquired implicitly through case exposure rather than explicit instruction, yet trainees disrupt attending physicians' diagnostic routines in ways that reduce premature closure. Second, with experience, nephrologists develop a contextually adaptive strategy, applying parsimony to routine presentations while shifting toward multifactorial reasoning for medically complex patients. Third, publicly funded system constraints create a structural bias toward Occam's razor, with time pressure and resource stewardship pushing clinicians toward the simplest defensible diagnosis regardless of case complexity.

Nephrology training produces diagnostically capable clinicians, despite a lack of didactic teaching. Diagnostic reasoning develops through unstructured exposure rather than deliberate instruction, leaving trainees without clear frameworks to recognise when to shift heuristics. These findings point toward specific and actionable reforms: explicit instruction in heuristic-switching, structured reflection embedded in clinical rotations, and training environments designed to counteract system-level pressures that conflate efficiency with diagnostic parsimony.