Purpose: To assess whether parathyroid hormone is associated with QT interval changes in critical ill patients presenting with renal impairment. Methods: This observational cohort study designed to examine ninety patients in the unit of intensive care who were admitted suffering from renal impairment whether as acute kidney injury or chronic kidney disease. Parathormone level, ECG and bedside echocardiography were done upon admission to the ICU. Results: Elevated PTH was associated with statistically significant longer corrected QT, (p-value = 0.002) with positive correlation (r = 0.326). The PTH level was statistically significant inversely correlated with EF (r = - 0.465), Na (r = - 0.226), ionized Ca2+ (r = - 0.222), and corrected Ca (r = - 0.222). The level of PTH was statistically significant positively correlated with creatinine (r = 0.216), K (r = 0.303), and PO4 (r = 0.214). The PTH level also showed a significant increase in patients with HTN compared to patients without HTN. There was an increased PTH level in patients with CKD when compared to non-CKD patients with a highly statistical significant difference. Moreover, a statistically significant increased PTH level was obtained in participants with ischemic heart disease as detected by the presence of RWMAs in echocardiography when compared to other non-ischemic participants without RWMAs. Conclusion: The abnormally high level of PTH is associated with more prolonged QTc intervals and is also associated with lower ejection fraction of the left ventricle.