End-Stage Kidney Disease of Unknown Etiology in Southern Iraq: Clinical Characteristics and a Distinct Cardiometabolic Profile Among Patients Receiving Maintenance Hemodialysis

In several hot, agricultural regions a large share of end-stage kidney disease (ESKD) has no identifiable cause, and this form of disease is now regarded as a separate entity, termed chronic kidney disease of uncertain etiology (CKDu). Whether ESKD of unknown etiology in southern Iraq differs clinically from ESKD with a recorded cause has not been examined. This cross-sectional analysis included all 394 adults receiving maintenance hemodialysis in the five units of Thi-Qar Governorate between September 2025 and January 2026. Patients in whom no primary renal diagnosis could be established were compared with patients with a recorded cause for demographic, comorbidity, and dialysis characteristics. Independent correlates of unknown etiology were identified with multivariable binary logistic regression. The etiology of ESKD was unknown in 62 patients (15.7%; 95% CI 12.5–19.7). The two groups were similar in age (52.2 ± 19.8 vs. 53.7 ± 16.6 years), sex, residence, duration of known CKD, dialysis vintage, dialysis frequency, and vascular access. Patients with unknown etiology less often had diabetes mellitus (19.4% vs. 47.9%), hypertension (69.4% vs. 86.4%), and cardiovascular disease (12.9% vs. 32.5%; all p ≤ 0.002). In multivariable analysis, diabetes (adjusted odds ratio [aOR] 0.34; 95% CI 0.16–0.69), hypertension (aOR 0.42; 0.21–0.82), and cardiovascular disease (aOR 0.41; 0.18–0.93) were independently associated with lower odds of unknown etiology, whereas age, sex, and dialysis vintage were not. About one in six patients on hemodialysis in Thi-Qar has ESKD of unknown cause. These patients are of working age and carry a markedly lower cardiometabolic burden than patients with a recorded cause, a profile that raises the possibility of a CKDu-like pattern, although occupational, environmental, and histopathological data were not available to confirm it. Systematic diagnostic work-up of these patients and studies of environmental and occupational exposures in southern Iraq are warranted.