Severe hyperphosphatemia and hypocalcemia caused by bowel preparation for colonoscopy using oral sodium phosphate in end-stage renal disease

Transient Hypocalcemia in a Dialysis Patient With Paget's disease and Presumed Renal Cell Carcinoma

A 68-year-old man with end-stage renal disease was hospitalized because of radicular pain and weakness in the left arm and hand. Sonography and computed tomography had recently shown a large right renal mass. On admission, magnetic resonance imaging demonstrated vertebral metastases with epidural extension, and radiotherapy was directed to the spine and kidney. Hypocalcemia was first noted on the fourth hospital day. A second computed tomography scan showed bleeding into and around the kidney, and arterial embolization was required to halt the bleeding. Hypocalcemia persisted for at least 27 days at values between 6.0 and 7.7 mg/dL and was consistently associated with ionized calcium concentrations less than or equal to 4.44 mg/dL. After an unrevealing search for a recognized cause, we attributed hypocalcemia to persistent sequestration of calcium in the right retroperitoneum. Exogenous supplementation eventually restored the concentration to normal. In the absence of renal and intestinal loss, hypocalcemia reflects abnormal flux of calcium from the extracellular compartment into tissue. Our patient's repository appears to have been a necrotic and hemorrhagic cancer. Tumor-induced sequestration of calcium should be included in the differential diagnosis of hypocalcemia.

Intermediate bioelectrolyte changes after phospho-soda or polyethylene glycol precolonoscopic laxatives in a population undergoing health examinations

BACKGROUND

Colonoscopy is a common procedure for diagnosing and screening colon cancer and other bowel-related diseases. Many studies have pointed out that using phospho-soda as a bowel preparation can cause obvious electrolyte abnormalities or acute kidney injury. Nonetheless, there are few studies related to its prevalence and risk factors in the population undergoing health examinations. Our aim was to compare the biochemical and electrolyte changes after using two commonly used bowel preparation regimens in this population.

METHODS

In this retrospective study, we collected data about participants who, before a screening colonoscopy, used oral phospho-soda laxatives in 2006, and those who used polyethylene glycol-based laxatives in 2005. Several serum biochemical and electrolyte profiles were compared between the two groups. Additional risk factors of hyperphosphatemia, a well-known side effect of phospho-soda, were also derived.

RESULTS

We enrolled a total of 2270 participants (1321 in 2005; 1449 in 2006). The basic demographic data of the two groups were not statistically different. Nonetheless, between the two groups, some serum biochemical and electrolytic data differed significantly: in those using oral phospho-soda laxatives, we found a higher prevalence of hyperuricemia, hypocalcemia, hypokalemia, hypernatremia and hyperphosphatemia. Further analyses showed that using oral phospho-soda laxatives was a risk factor for hyperphosphatemia; conversely, being male was a protective factor.

CONCLUSION

Oral phospho-soda laxatives indeed influence the biochemical and electrolyte profiles of persons undergoing health examinations. One should be careful when interpreting bioelectrolytic data while using phospho-soda as a bowel preparation.

The safety of osmotically acting cathartics in colonic cleansing

Efficient cleansing of the colon before a colonoscopy or a radiological examination is essential. The osmotically acting cathartics (those given the Anatomical Therapeutic Chemical code A06AD) currently used for this purpose comprise products based on three main substances: sodium phosphate, combinations of polyethylene glycol and electrolyte lavage solutions (PEG-ELS), and magnesium citrate. All these preparations give adequate cleansing results and have similar profiles in terms of the frequency and type of mild to moderate adverse effects. However, serious adverse events, such as severe hyperphosphatemia and irreversible kidney damage owing to acute phosphate nephropathy, have been reported after use of sodium-phosphate-based products. The aim of this Review is to provide an update on the potential safety issues related to the use of osmotically acting cathartics, especially disturbances of renal function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte balance. Sodium-phosphate-based products can occasionally cause irreversible kidney damage and should not be routinely used in bowel-cleansing procedures.

Systematic review: adverse event reports for oral sodium phosphate and polyethylene glycol

BACKGROUND

Screening colonoscopy exposes healthy patients to the risk of serious adverse events associated with bowel preparation. Randomized controlled trials are not an effective method for evaluating this risk.

AIM

To search published literature in order to characterize the risk of adverse events associated with oral polyethylene glycol (PEG) or sodium phosphate (NaP).

METHODS

A systematic review identified case reports of any serious events associated with PEG or NaP. Reports to the Food and Drug Administration (FDA) were also examined.

RESULTS

Fifty-eight publications of significant events in 109 patients using NaP and 22 patients using PEG were identified. As the total number of prescriptions issued is unknown, rates for the two agents cannot be directly compared. Most commonly reported were electrolyte disturbances, renal failure and colonic ulceration for NaP and Mallory-Weiss tear, electrolyte disturbances and allergic reactions for PEG between January 2006 and December 2007; there were 171 cases of renal failure reported to the FDA following use of NaP and 10 following PEG.

CONCLUSIONS

Adverse events following bowel preparation are uncommon, but potentially serious. Given that many of these patients are healthy individuals undergoing screening, the benefit/risk ratio must be carefully considered when deciding which preparation to prescribe in individual patients.

Acute phosphate nephropathy-an emerging threat

BACKGROUND

Acute phosphate nephropathy (APN) is a clinicopathological entity causing renal failure, after ingestion of oral sodium phosphate solution (OSPS). Approximately 25 cases have been described, but OSPS is still widely used. This study reports a further 5 cases and discusses the ever-growing significance of APN.

METHODS

Five cases of APN were included, 3 retrospectively whereas 2 were diagnosed prospectively. In all, use of OSPS was established, and other causes of nephrocalcinosis were excluded.

RESULTS

Average age was 67.4 +/- 7.0 years, with a female preponderance (4:1). All patients had hypertension. Baseline serum creatinine: 0.7 to 1.2 mg/dL (creatinine clearance: 52 to 77 mL/min). Time from colonoscopy to presentation was 56 +/- 36 days. Serum creatinine levels at presentation: 1.4 to 3.6 mg/dL. Time from colonoscopy to renal biopsy was 123 +/- 88 days. Urinalysis showed minimal proteinuria, leucocyturia, and hematuria. One patient had renal glucosuria. All patients were anemic (hemoglobin 8.8-11.4 gr/dL). Serum calcium and phosphate were normal. One required hemodialysis. Mean follow-up was 36 +/- 17 months. Serum creatinine levels at end of follow-up were 1.3 to 3.1 mg/dL. Renal function did not recover completely in any patient. Four required long-term erythropoietin treatment. The prominent histopathological findings were calcium-phosphate tubular depositions (100%), interstitial fibrosis (80%), hypertensive changes (80%), and acute tubular degenerative and regenerative changes (60%).

CONCLUSIONS

APN is a serious, irreversible renal complication of OSPS. It is probably under-recognized. Risk factors include female gender, older age, hypertension, and renal failure, although it may occur with preexisting normal renal function.

Risk of further decline in renal function after the use of oral sodium phosphate or polyethylene glycol in patients with a preexisting glomerular filtration rate below 60 ml/min

OBJECTIVES

The aim of this study was to estimate the risk of further creatinine increase in patients with preexisting renal disease after the use of oral sodium phosphate (OSP) versus polyethylene glycol (PEG), and to study usage patterns of OSP in relation to renal function.

METHODS

A cohort study was done using clinical records and electronic patient information from the Henry Ford Health System (HFHS) in patients who had used either OSP or PEG for colonoscopy between February 1999 and April 2006. Among patients with an estimated GFR < 60 ml/min before colonoscopy, we identified cases with an unexplained creatinine increase of > or = 0.5 mg/dl within 14 days after colonoscopy.

RESULTS

We identified 7,971 OSP and 1,511 PEG users. Relative use of OSP versus PEG decreased from 88.0% before 2004 to 48.4% in 2006. 70.2% of OSP users had no recorded creatinine determination within 60 days before colonoscopy, and this proportion did not decrease over time. The study population included 317 patients with a baseline GFR < 60 ml/min, and we identified one case with an unexplained creatinine increase > or = 0.5 mg/dl among 191 PEG users (0.5%) versus eight cases among 126 OSP users (6.3%). Unadjusted and adjusted relative risk estimates on comparing OSP with PEG were 12.1 (95% CI, 1.5-95.8) and 12.6 (95% CI, 1.5-106.5), respectively.

CONCLUSIONS

In patients with preexisting renal disease, OSP use was associated with an increased risk of aggravated renal dysfunction versus PEG. Creatinine measurement with GFR estimation should be done before OSP administration in order to avoid its use in patients with renal disease.

Adverse renal and metabolic effects associated with oral sodium phosphate bowel preparation

Colorectal cancer can be prevented by the removal of adenomatous polyps during screening colonoscopy, but adequate bowel preparation is required. Oral sodium phosphate (OSP), an effective bowel purgative, is available over the counter and requires a substantially lower volume than polyethylene glycol-based preparative agents. Accumulating reports implicate OSP in electrolyte disturbances as well as acute kidney injury (AKI) in a syndrome termed phosphate nephropathy (a form of nephrocalcinosis). Despite published case reports and case series, the actual incidence, risk factors, and natural history of phosphate nephropathy remain largely undefined. Several recent observational studies have provided new information on these important issues while supporting a link between OSP and acute phosphate nephropathy as well as the development of chronic kidney disease in elderly patients, many of whom had a normal serum creatinine at the time of OSP ingestion. This review summarizes current knowledge about the renal complications of OSP, risk factors for its development, and the pathophysiology of acute and chronic kidney damage in nephrocalcinosis.

Symptomatic hypocalcemia after sodium phosphate preparation in an adult with asymptomatic hypoparathyroidism

Sodium phosphate is widely used as a bowel cleansing preparation. Its use is, however, not without risk. It can induce serious adverse effects like hypocalcemia, hyperphosphatemia and renal failure. In this case, a 75-year-old woman without known contraindications developed hypocalcemic tetany, hyperphosphatemia and renal failure after oral sodium phosphate. Asymptomatic hypoparathyroidism owing to previous thyroid surgery was identified as a new contributing risk factor for this complication.