Incidence and outcome of acute phosphate nephropathy in Iceland

New Ultra Low Volume Bowel Preparation and Overview of Existing Bowel Preparations

BACKGROUND

Adequate bowel cleansing is essential in achieving a good quality colonoscopy. However, one of the barriers to achieving high-quality bowel cleansing is the patient's tolerability. Different bowel preparations have been developed to improve tolerability while maintaining adequate bowel cleansing.

OBJECTIVES

We aim to explore the pros and cons of commonly used bowel preparations, particularly highlighting the new ultra-low volume bowel preparation.

METHODS

Extensive literature search was carried out on various databases to evaluate the effectiveness and side effects of different bowel cleansing agents, including findings of recent clinical trials on ultra-low bowel preparation.

RESULTS

Polyethylene glycol (PEG) has been commonly used as a bowel prep. Due to its high volume required to ingest to achieve an adequate effect, it has been combined with various adjuncts to reduce the volume to make it more tolerable. Magnesium and phosphate-based preps can achieve low volume, but they can be associated with multiple side effects, mainly electrolyte disturbances. Ultra low volume prep (NER1006) was achieved by combing PEG with ascorbic acid, and its efficacy and side effects were demonstrated in three noninferiority studies.

CONCLUSION

It is important to consider patient preferences, co-morbidities and tolerability, and efficacy and side effect profiles when choosing bowel prep for patients undergoing colonoscopy. New ultra-low bowel prep showed promising results in initial clinical trials, but further real-world post-marketing data will inform its value in clinical practice.

Biopsy-proven acute phosphate nephropathy: A case report

BACKGROUND

Acute phosphate nephropathy (APN) is a disease that can occur when exposed to high doses of phosphate. The most common cause of APN is the use of oral sodium phosphate for bowel cleansing preparations. However, there are other less commonly known sources of phosphate that are equally important. To date, our literature search did not identify any report of excessive dietary phosphate as a cause of APN.

CASE SUMMARY

We report an unusual case of a 39-year-old diabetic male who presented with epigastric pain and oliguria. Work-up showed elevated serum creatinine, potassium, and calcium-phosphate product, and metabolic acidosis. The patient was admitted in the intensive care unit and received emergent renal replacement therapy. Kidney biopsy revealed tubular cell injury with transparent crystal casts positive for Von Kossa staining, which established the diagnosis of APN.

CONCLUSION

This case confirmed that APN may occur with other sources of phosphorus, highlighting the importance of good history taking and kidney biopsy in patients with predisposing factors for APN. Raising awareness on the possibility of APN and its timely recognition and management is imperative so that appropriate measures can be instituted to prevent or delay its progression to end stage renal disease.

Evaluation of phosphorus, calcium, and magnesium content in commercially available foods formulated for healthy cats

Background

High dietary phosphorus (P) and low calcium‐to‐phosphorus ratio (Ca:P) are associated with kidney damage in cats. There are no established guidelines for dietary P maximum for cats.

Objectives

To quantify crude protein, P, Ca, and magnesium (Mg) concentrations in cat foods and compare among food formats (dry, canned, raw), primary protein ingredients, protein concentrations (low, moderate, high), grain‐free versus grain‐containing foods, foods intended for adult maintenance versus all life stages, and cost.

Samples

Eighty‐two commercial nonprescription cat foods.

Methods

Descriptive study. Mineral concentrations were measured using inductively coupled argon plasma‐optical emission spectroscopy. Crude protein was measured using the Dumas nitrogen combustion method. Mineral and crude protein concentrations were compared among food categories.

Results

Twenty‐seven foods contained ≥3.6 g P/1000 kcal metabolizable energy (ME), of which 7 exceeded 4.8 g/1000 kcal ME. Thirteen foods had low Ca:P ratio (≤1.0). The low‐protein diet group had no products ≥3.6 g P/1000 kcal ME, which was significantly different compared to the high‐protein diet group (52% of products had ≥3.6 g P/1000 kcal ME; P = .01). No significant differences in P content and Ca:P ratio were found among other diet categories. Canned foods had significantly lower Mg compared to dry (P < .001) and raw (P = .007) foods. Declared minimum P and Ca were significantly lower than analyzed concentrations (P = .0005 and P = .003, respectively).

Conclusions and Clinical Importance

The high number of foods with high P and low Ca suggest that pet food regulatory reform should be considered.

Phosphate nephropathy: an avoidable complication of bowel preparation for colonoscopy

It is known that oral sodium phosphate, used as bowel preparation for colonoscopy, can cause acute phosphate nephropathy, a potentially severe and irreversible form of acute kidney injury. Due to these safety concerns, guidelines have advised against the routine use of this agent for a decade. We present a case report and biopsy series that demonstrate that oral sodium phosphate is still being used and that cases of APN are still occurring, in Australia.

Evaluation of intestinal phosphate binding to improve the safety profile of oral sodium phosphate bowel cleansing

Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP) is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI) referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis) are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage) with a 12h time interval induced bowel cleansing (severe diarrhea) and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline). Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline) and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections). Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide) was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.

The colorectal cancer mortality-to-incidence ratio as an indicator of global cancer screening and care

BACKGROUND

Disparities in cancer screening, incidence, treatment, and survival are worsening globally. The mortality-to-incidence ratio (MIR) has been used previously to evaluate such disparities.

METHODS

The MIR for colorectal cancer is calculated for all Organisation for Economic Cooperation and Development (OECD) countries using the 2012 GLOBOCAN incidence and mortality statistics. Health system rankings were obtained from the World Health Organization. Two linear regression models were fit with the MIR as the dependent variable and health system ranking as the independent variable; one included all countries and one model had the "divergents" removed.

RESULTS

The regression model for all countries explained 24% of the total variance in the MIR. Nine countries were found to have regression-calculated MIRs that differed from the actual MIR by >20%. Countries with lower-than-expected MIRs were found to have strong national health systems characterized by formal colorectal cancer screening programs. Conversely, countries with higher-than-expected MIRs lack screening programs. When these divergent points were removed from the data set, the recalculated regression model explained 60% of the total variance in the MIR.

CONCLUSIONS

The MIR proved useful for identifying disparities in cancer screening and treatment internationally. It has potential as an indicator of the long-term success of cancer surveillance programs and may be extended to other cancer types for these purposes.

Bowel preparation for colonoscopy with magnesium sulphate and low-volume polyethylene glycol

BACKGROUND

Patient compliance with bowel cleansing procedures represents one of the most objectionable aspects of colonoscopy. Adverse reactions to the purgative may result in failure to complete the preparation, inadequate visualization of the colon, polyp and even carcinoma miss rate and unwillingness to attend a follow-up colonoscopy. The primary objective of the study was to evaluate the effectiveness of bowel cleansing with magnesium sulphate and low-volume polyethylene glycol (PEG) with electrolytes. The second objective was to evaluate whether bowel cleansing was better in participants scheduled for morning colonoscopies or afternoon colonoscopies.

PATIENTS AND METHODS

Magnesium sulphate mineral water (2 l) and 2 l of low-volume PEG and electrolytes solution were used as our bowel cleansing protocol. A total of 13 914 participants, who participated in the Slovenian colorectal cancer screening programme in the period between 2009 and 2011, were included.

RESULTS

Excellent bowel preparation was achieved in 11 484 (82.61%) participants; 1894 (13.62%) participants had good bowel preparation, 439 (3.16%) participants had fair bowel preparation and 85 (0.61%) participants had poor bowel preparation. Better results were achieved in the afternoon colonoscopies and in younger participant groups (P<0.001). No serious side effects of bowel cleansing were reported.

CONCLUSION

This is the first study to use magnesium sulphate mineral water and PEG plus electrolytes for bowel cleansing. We found excellent bowel cleansing in 82.61% participants and in more participants if colonoscopy was performed in the afternoon.

Optimal and safe bowel preparation for colonoscopy

Effective colonoscopy requires an adequate level of cleansing as a basic component. This review will describe a compact review about general considerations in bowel preparation for colonoscopy and specific considerations for various patients. A low-fiber diet instead of a regular diet on the day before colonoscopy is an independent predictor of adequate bowel preparation. Improved bowel cleansing does not result from the routine use of enemas or prokinetics in addition to oral bowel preparation. For morning colonoscopy, a split method of 4 L polyethylene glycol on the day before and the day of colonoscopy is recommended, while patients scheduled for afternoon colonoscopy typically receive a full method of 4 L polyethylene glycol on the day of the procedure. Valid alternatives are 2 L polyethylene glycol plus ascorbic acid or 2 L sodium picosulphate plus magnesium citrate. Although there are no statistically significant differences between polyethylene glycol and oral sodium phosphate for colon cleansing, polyethylene glycol-based bowel preparation is advisable in most situations because of safety concerns.

Meta-analysis: the relative efficacy of oral bowel preparations for colonoscopy 1985-2010

BACKGROUND

Previous reviews of bowel preparation for colonoscopy have given contradictory answers.

AIM

To provide a definitive insight, using PRISMA-compliant methodology.

METHODS

A comprehensive literature review identified randomised controlled trials comparing bowel preparation regimens. Data for quality of bowel preparation were pooled in multiple meta-analyses exploring a range of inclusion criteria.

RESULTS

A total of 104 qualifying studies were identified, the majority of which involved comparisons of sodium phosphate (NaP) or polyethylene glycol (PEG). There was no significant difference demonstrated between NaP and PEG overall (OR = 0.82; 95% CI = 0.56-1.21; P = 0.36). Cumulative meta-analysis demonstrated that this conclusion has been qualitatively similar since the mid 1990s, with little quantitative change for the past 10 years. Amongst studies with previous day dosing in both study arms there was a significant advantage in favour of PEG (OR = 1.78; 95% CI = 1.13-2.81; P = 0.006). Studies focussing on results in the proximal colon also favoured PEG (OR = 2.36; 95% CI = 1.16-4.77; P = 0.012). PEG was also significantly more effective than non-NaP bowel preparation regimens (OR = 2.02; 95% CI = 1.08-3.78; P = 0.03). Other comparisons showed no significant difference between regimens.

CONCLUSIONS

Although there is no compelling evidence favouring either of the two most commonly used bowel preparation regimens, this may reflect shortcomings in study design. Where studies have ensured comparable dosage, or the clinically relevant outcome of proximal bowel clearance is considered, PEG-based regimens offer the most effective option.