Estimated GFR Decline Following Sodium Phosphate Enemas Versus Polyethylene Glycol for Screening Colonoscopy: A Retrospective Cohort Study

Toxicity of phosphate enemas - an updated review

INTRODUCTION

Enemas containing phosphate are widely prescribed and may cause important adverse effects. A systemic review published in 2007 reported the literature on the adverse effects of phosphate enemas from January 1957 to March 2007 and identified 12 deaths. These were thought due to electrolyte disturbances, heart failure and kidney injury. These data raised concerns about the use of phosphate enemas in routine practice. Newer osmotic-based enema alternatives are now available that do not contain absorbable ions. We sought to review the literature since this review and evaluate the latest data on the toxicity of phosphate-containing enemas. To gain a fuller picture we included case series and larger studies as well as case reports.

OBJECTIVES

To review the toxicity of phosphate enemas, particularly with respect to acute metabolic consequences and their associated clinical features. To identify risk factors for metabolic toxicity and consider whether phosphate enemas should be relatively contra-indicated in specific patient groups.

METHODS

A systematic literature review was conducted in PubMed, Google Scholar, and Cochrane Reviews (2005-2021) using the search terms 'phosphate enema or sodium phosphate enema' or 'phosphate-based enema' or (phosphate AND enema) or (Fleet AND enema) or 'sodium phosphate laxatives' or 'sodium phosphate catharsis' or 'sodium phosphate cathartic'. Relevant papers were read, and data were extracted.

RESULTS

The searches identified 489 papers of which 25 were relevant: seven papers were case reports or small case series of metabolic abnormalities from the use of phosphate enemas in nine children, six were case reports on 16 adults. Nine papers were large case series or clinical studies that included data on systemic metabolic effects, of varying size from 24 healthy volunteers to a cohort of 70,499 patients. Case reports identified seven adult deaths but none in children. Children most often presented with decreased consciousness (6/9), and tetany (4/9). In adults overall only five cases had clinical features reported, hypotension was seen in four and QT prolongation in two. Treatment was generally symptomatic, with intravenous fluid and calcium salts for electrolyte changes and hypocalcaemia, and vasopressors for severe hypotension. Haemodialysis was used in three children and peritoneal dialysis in one, all of whom survived. In adults, haemodialysis did not prevent death in two of four cases in whom it was used. Common factors underlying toxicity were inappropriately high phosphate dose, or enema retention, both resulting in greater absorption of phosphate. Associated pre-disposing conditions included Hirschsprung disease in children and co-morbidity and renal impairment (2/5) in older adults. Absolute reported changes in serum phosphate or calcium were not accurate indicators of outcome. Larger case series and clinical trials confirm an acute effect of phosphate enemas on serum phosphate, which was related to both dose and retention time. These effects were not seen with non-phosphate preparations. In these cases series, adverse events were rarely reported.

CONCLUSION

Phosphate enemas are potentially toxic, particularly in young children with Hirschsprung disease and in the elderly with co-morbidity. Raised awareness of the risk of phosphate enemas is still required. Other less toxic enema preparations are available and should be considered in patients at extremes of age. If phosphate enemas are the only clinical option careful monitoring of biochemical sequelae should be undertaken.

Novel intestinal dialysis interventions and microbiome modulation to control uremia

PURPOSE OF REVIEW

In patients with chronic kidney disease (CKD), the gut plays a key role in the homeostasis of fluid and electrolyte balance and the production and disposal of uremic toxins. This review summarizes the current evidence on the gut-targeted interventions to control uremia, fluid overload, hyperkalemia and hyperphosphatemia in CKD.

RECENT FINDINGS

Studies have emerged that support the concept of intestinal dialysis, such as colonic perfusion with a Malone antegrade continence enema stoma or colonic irrigation with a rectal catheter, as a promising adjuvant approach to control uremia in CKD, although most findings are preliminary. The use of AST-120, an oral adsorbent, has been shown to reduce circulating levels of indoxyl sulfate and p-cresol sulfate and have potential renoprotective benefits in patients with advanced CKD. Diarrhea or inducing watery stools may modulate fluid retention and potassium and phosphorus load. Accumulating evidence indicates that plant-based diets, low-protein diets, and pre-, pro-, and synbiotic supplementation may lead to favorable alterations of the gut microbiota, contributing to reduce uremic toxin generation. The effects of these gut-targeted interventions on kidney and cardiovascular outcomes are still limited and need to be tested in future studies including clinical trials.

SUMMARY

Interventions aimed at enhancing bowel elimination of uremic toxins, fluid and electrolytes and at modulating gut microbiota may represent novel therapeutic strategies for the management of uremia in patients with CKD.

Diet and Chronic Kidney Disease

Kidney disease affects almost 15% of the US population, and prevalence is anticipated to grow as the population ages and the obesity epidemic continues due to Western dietary practices. The densely caloric Western diet, characterized by high animal protein and low fruit and vegetable content, has fueled the growth of chronic diseases, including chronic kidney disease. The glomerulus or filtering unit of the kidney is very susceptible to barotrauma, and diets high in animal protein impede the glomerulus' ability to protect itself from hemodynamic injury. High animal protein intake combined with low intake of fruits and vegetables also leads to a high net endogenous acid production requiring augmentation of ammonium excretion in order to prevent acidosis. This higher workload of the kidney to maintain a normal serum bicarbonate level may further exacerbate kidney disease progression. This article reviews the potential mechanisms whereby several key characteristics of the typical Western diet may impact kidney disease incidence and progression. Reducing animal protein intake and egg yolk and increasing intake of fruits and vegetables and fiber may prevent or delay end-stage renal disease, but few clinical trials have examined vegetarian diets for management of chronic kidney disease. More research is needed to determine optimal dietary patterns for the prevention of kidney disease and its progression.

Drug-Induced Kidney Stones and Crystalline Nephropathy: Pathophysiology, Prevention and Treatment

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favour crystallisation in the urine. Among them, drugs used for the treatment of patients with human immunodeficiency, namely atazanavir and other protease inhibitors, and sulphadiazine used for the treatment of cerebral toxoplasmosis, are the most frequent causes. Besides these drugs, about 20 other molecules may induce nephrolithiasis, such as ceftriaxone or ephedrine-containing preparations in subjects receiving high doses or long-term treatment. Calculi analysis by physical methods including infrared spectroscopy or X-ray diffraction is needed to demonstrate the presence of the drug or its metabolites within the calculi. Some drugs may also provoke heavy intra-tubular crystal precipitation causing acute renal failure. Here, the identification of crystalluria or crystals within the kidney tissue in the case of renal biopsy is of major diagnostic value. The second group includes drugs that provoke the formation of urinary calculi as a consequence of their metabolic effects on urinary pH and/or the excretion of calcium, phosphate, oxalate, citrate, uric acid or other purines. Among such metabolically induced calculi are those formed in patients taking uncontrolled calcium/vitamin D supplements, or being treated with carbonic anhydrase inhibitors such as acetazolamide or topiramate. Here, diagnosis relies on a careful clinical inquiry to differentiate between common calculi and metabolically induced calculi, of which the incidence is probably underestimated. Specific patient-dependent risk factors also exist in relation to urine pH, volume of diuresis and other factors, thus providing a basis for preventive or curative measures against stone formation.

Sodium phosphate enemas do not worsen renal function among hospitalized patients with mild to moderate renal failure: a matched, case-control study

BACKGROUND

Sodium phosphate enemas (SPEs) are widely used among hospitalized patients despite their potential to worsen renal failure.

AIM

We decided to assess the extent to which this side effect is clinically relevant.

DESIGN

We conducted a matched case-control, retrospective study in a cohort of hospitalized patients.

METHODS

Patients treated and untreated with SPEs were matched for age, gender, baseline creatinine, usage of certain medications and several background diagnoses. Three groups of matched patients (whole study cohort, patients with baseline creatinine > 1.5 mg/dl and those with baseline creatinine > 2 mg/dl) were compared with regards to their creatinine and blood electrolyte concentrations during 3 consecutive hospitalization days after SPE application.

RESULTS

Four hundred and twelve patients were included in this study of which 206 were treated by single SPEs. Exact matching was done for the whole study cohort, for 108 patients with baseline creatinine > 1.5 mg/dl and for 58 patients with baseline creatinine > 2 mg/dl. During 3 consecutive days after SPEs, the maximal blood concentrations of creatinine, phosphor and potassium did not differ significantly between treated patients and matched controls, in all three patients' groups.

CONCLUSION

Application of SPEs neither seem to worsen mild to moderate renal failure, nor are associated with hyperphosphatemia or hyperkalemia in patients hospitalized in internal medicine departments.

Phosphate enemas and GFR decline: it's premature to sound the alarm

Oral sodium phosphate solutions can cause acute phosphate nephropathy, resulting in acute kidney injury and chronic kidney disease. A recent cohort study suggests that phosphate enemas may also be associated with a decline in glomerular filtration rate, but further study is needed to establish a causal relationship.