Recently there is renewed interest in the association between type 2 diabetes and colorectal carcinoma (1). Some authorities have advocated more intensive colonoscopy screening in patients with diabetes (2). We recently managed two diabetic patients who developed acute renal failure following elective colonoscopy. The clinical presentation and biochemical parameters of these two patients are summarized in Table 1.
Both of the patients described had normal renal function at baseline, yet presented with acute renal failure within a few days following bowel preparation and colonoscopy, thus strongly implicating the bowel preparation in the development of the acute renal failure. Both patients received oral sodium phosphate (OSP) solution for bowel cleansing. OSP promotes colon evacuation by drawing large amounts of water into the colon and has been shown to be more effective and better tolerated than polyethylene glycol (PEG) solution. However, recent studies suggest that some patients given OSP are at risk of renal failure due to acute phosphate nephropathy. In a series of 31 cases of renal impairment with renal biopsies showing deposits of tubular calcium phosphate, the risk was highest among patients with preexisting renal impairment, elderly patients, and patients with hypertension or concurrent use of ACE inhibitor or angiotensin receptor blocker (ARB). In that series, 21 patients presented with acute renal failure, of which 4 had diabetes, with age ranging between 44 and 66 years. In a few patients, acute renal failure was discovered within 3 days of colonoscopy, at which time hyperphosphatemia was documented (3).
The U.S. Food and Drug Administration has recently issued an alert advising against the use of OSP products in patients with kidney disease, impaired renal function or perfusion, dehydration, or uncorrected electrolyte abnormalities. OSP should be used with caution in patients taking diuretics, ACE inhibitors, ARBs, and nonsteroidal anti-inflammatory drugs (NSAIDs) (4). In the recently published consensus document on bowel preparation before colonoscopy (5), there was no specific advice given for patients with diabetes aside from the statement that patients with diabetes have significantly poorer preparations with PEG solution than those without diabetes. Patients with diabetes often have reduced renal perfusion despite normal serum creatinine. Incipient diabetic nephropathy is marked by the presence of microalbuminuria, a powerful predictor of subsequent diabetic nephropathy. Our experience suggests that patients with diabetes and normal renal function tests may be at increased risk of acute phosphate nephropathy after taking OSP. Clinicians should consider avoiding the use of OSP in patients with diabetes undergoing colonoscopy. Use of an osmotically balanced cleansing agent that does not cause significant shift of fluid and electrolytes, such as PEG, is likely to be a safer alternative (6). For patients receiving drugs that alter electrolyte balance, such as diuretics, ACE inhibitors, or ARBs, it may be prudent to withhold these drugs temporarily before OSP. Close monitoring of hydration status, glycemic control, and renal function is mandatory during the preparation and after colonoscopy in patients with diabetes.
Clinical presentation and biochemical findings of two patients with diabetes presenting with acute renal failure after sodium phosphate bowel preparation
| . | Patient 1 (T.T.H.) . | Patient 2 (U.T.) . | Normal range . |
|---|---|---|---|
| Age/sex | 75/male | 80/female | |
| Other medical history | Hypertension, microalbuminuria, paroxysmal atrial fibrillation | Hypertension, hyperlipidemia, diabetic retinopathy | |
| Baseline creatinine | 80 (62–106 μmol/l) | 79 (44–80 μmol/l) | |
| Diabetes medications | Gliclazide, metformin | Gliclazide, metformin | |
| Other medications | Perindopril, warfarin, sotalol, nifedipine | Aspirin, amitriptyline, famotidine | |
| Presenting complaint | Diarrhea, decreased consciousness | Hypoglycemia, diarrhea and vomiting | |
| Days after colonoscopy | 4 | 3 | |
| Sodium (mmol/l) | 133 | 132 | 134–145 |
| Potassium (mmol/l) | 6.8 | 4.7 | 3.5–5.1 |
| Urea (mmol/l) | 21.4 | 16.8 | 3.4–8.9 |
| Creatinine (μmol/l) | 924 (62–106) | 629 (44–80) | |
| Calcium (mmol/l) | 2.51 | 2.16 | 2.15–2.55 |
| Phosphate (mmol/l) | 4.19 | 2.04 | 0.82–1.40 |
| Lactate (mmol/l) | 17.3 | 7.2 | 0.7–2.1 |
| Dialysis required | CRRT for 5 days | No | |
| Last creatinine (μmol/l) | 115 | 101 |
| . | Patient 1 (T.T.H.) . | Patient 2 (U.T.) . | Normal range . |
|---|---|---|---|
| Age/sex | 75/male | 80/female | |
| Other medical history | Hypertension, microalbuminuria, paroxysmal atrial fibrillation | Hypertension, hyperlipidemia, diabetic retinopathy | |
| Baseline creatinine | 80 (62–106 μmol/l) | 79 (44–80 μmol/l) | |
| Diabetes medications | Gliclazide, metformin | Gliclazide, metformin | |
| Other medications | Perindopril, warfarin, sotalol, nifedipine | Aspirin, amitriptyline, famotidine | |
| Presenting complaint | Diarrhea, decreased consciousness | Hypoglycemia, diarrhea and vomiting | |
| Days after colonoscopy | 4 | 3 | |
| Sodium (mmol/l) | 133 | 132 | 134–145 |
| Potassium (mmol/l) | 6.8 | 4.7 | 3.5–5.1 |
| Urea (mmol/l) | 21.4 | 16.8 | 3.4–8.9 |
| Creatinine (μmol/l) | 924 (62–106) | 629 (44–80) | |
| Calcium (mmol/l) | 2.51 | 2.16 | 2.15–2.55 |
| Phosphate (mmol/l) | 4.19 | 2.04 | 0.82–1.40 |
| Lactate (mmol/l) | 17.3 | 7.2 | 0.7–2.1 |
| Dialysis required | CRRT for 5 days | No | |
| Last creatinine (μmol/l) | 115 | 101 |
CRRT, continuous renal replacement therapy.
