NSAID nephrotoxicity revisited: acute renal failure due to parenteral ketorolac

What is the most effective and safest Non-steroidal anti-inflammatory drug for treating osteoarthritis in patients with comorbidities?

INTRODUCTION

Understanding what the most effective and safe non-steroidal anti-inflammatory drug (NSAID) is for managing osteoarthritis (OA) is complicated. OA is prevalent worldwide and people living with OA commonly have multiple comorbidities. The efficacy and safety of NSAIDs in a patient are influenced by their intrinsic and extrinsic factors. Current guidelines recommend the lowest dose for the shortest duration, monitoring patients for risk factors and comorbidities but generally do not specify, which NSAID is most suitable for a patient with specific comorbidities.

AREAS COVERED

This paper looks at the mechanism of action of all NSAIDs and reviews the current literature concerning their safety in patients with and without comorbidities. Relevant publications were identified by searching PubMed and Cochrane Library using key terms. The search was conducted from inception to 18 July 2023 and included results published before 18 July 2023. The search results and their references were then manually reviewed.

EXPERT OPINION

In the paper, we determine whether the current practice of 'lowest dose for shortest duration' is in fact the best approach for prescribing NSAIDs and identify which NSAIDs are most suitable given a patient's risk factors and comorbidities. Our aim is to help guide health professionals in recommending the most suitable NSAID for each patient.

Kidney damage from nonsteroidal anti-inflammatory drugs-Myth or truth? Review of selected literature

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely available drugs with anti-inflammatory and analgesic properties. Their mechanism of action is associated with the enzymes of the arachidonic acid cycle (cyclooxygenases: COX-1 and COX-2). The cyclooxygenase pathway results in the formation of prostanoids (prostaglandins [PGs], prostacyclins, and thromboxanes). It affects various structures of the human body, including the kidneys. Medical literature associates the usage of NSAIDs with acute kidney injury (AKI), tubulointerstitial nephritis (TIN), as well as nephrotic syndrome and chronic kidney disease (CKD). AKI associated with the chronic consumption of NSAIDs is mainly attributed to pharmacological polytherapy and the presence of cardiovascular or hepatic comorbidities. The pathomechanism of AKI and CKD is associated with inhibition of the biosynthesis of prostanoids involved in the maintenance of renal blood flow, especially PGE2 and PGI2. It is suggested that both COX isoforms play opposing roles in renal function, with natriuresis increased by COX-1 inhibition followed by a drop in a blood pressure, whereas COX-2 inhibition increases blood pressure and promotes sodium retention. TIN after NSAID use is potentially associated with glomerular basement membrane damage, reduction in pore size, and podocyte density. Therefore, nephrotic proteinuria and impairment of renal function may occur. The following article analyzes the association of NSAIDs with kidney disease based on available medical literature.

NSAIDs in CKD: Are They Safe?

The management of pain in patients with chronic kidney disease (CKD) is challenging for many reasons. These patients have increased susceptibility to adverse drug effects due to altered drug metabolism and excretion, and there are limited safety data for use in this population despite a high pain burden. Nonsteroidal anti-inflammatory drugs (NSAIDs) have long been regarded as dangerous for use in patients with CKD because of their risk for nephrotoxicity and thus alternative classes of analgesics, including opioids, have become more commonly used for pain control in this population. Given the well-established risks that opioids and other analgesics pose, further characterization of the risk posed by NSAIDs in patients with CKD is warranted. NSAID use has been associated with acute kidney injury, progressive loss of glomerular filtration rate in CKD, electrolyte derangements, and hypervolemia with worsening of heart failure and hypertension. The risk for these nephrotoxicity syndromes is modified by many comorbid conditions, risk factors, and characteristics of use, and in patients with CKD, the risk differs between levels of glomerular filtration rate. In this review, we offer recommendations for the cautious use of NSAIDs in the CKD population after careful consideration of these risk factors on an individualized basis.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

Echinomycin did not affect the safety of fracture healing: an experimental pilot study on a murine femur fracture model

Background

There is a need for effective drugs in the prevention and treatment of heterotopic ossifications (HO) after fractures. Echinomycin has been shown to prevent formation of HO in an animal model. However, before it may be considered as an option against HO, it needs to be studied whether it prevents fracture healing similar to non-steroidal anti-inflammatory drugs (NSAIDS). Therefore, the hypothesis was that echinomycin prevents fracture healing and callus formation.

Methods

In an experimental murine pilot study, standard blunt femur fractures were induced and retrograde intramedullary compression fixation of the femur was performed. The treatment group (n = 8) received echinomycin (0.3 mg/kg body weight) and the control group (n = 8) did not receive echinomycin. The fractures and implant positions were verified by conventional X-rays immediately postoperatively. As the primary outcome variable, fracture healing (osseous consolidation) was evaluated by conventional X-rays and micro-computed tomography (CT) scans after ten weeks and graded as healed, partial or complete pseudarthrosis. The secondary outcome, callus formation, was graded semi-quantitatively from 0 (mostly absent) to 3 (maximum).

Results

Fracture healing was present in all living cases after ten weeks concerning the treatment group. Partial pseudarthrosis was seen in two cases, one in the treatment and another one in the control group. Complete pseudarthrosis was seen in one case of the control group after an open fracture. Callus formation was similar in both groups with a mean grade of 1.5 within each group. Two cases of the treatment group died.

Conclusion

As a novel finding, echinomycin did not inhibit fracture healing or callus formation in this in vivo murine standard femur fracture model pilot study. Further studies involving a larger number of cases, quantitative assessment with CT scans and histopathological analysis are needed before generalizing the results of this pilot study.

A Randomized Clinical Trial of Nefopam versus Ketorolac Combined With Oxycodone in Patient-Controlled Analgesia after Gynecologic Surgery

OBJECTIVES

Nefopam is a centrally-acting non-opioid analgesic, which has no effect on bleeding time and platelet aggregation. There has been no study about nefopam and oxycodone combination for postoperative analgesia. In this study, we present efficacy and side effects of nefopam/oxycodone compared with ketorolac/oxycodone in patient-controlled analgesia (PCA) after gynecologic surgery.

METHODS

120 patients undergoing gynecologic surgery were divided randomly into two groups: Nefopam group treated with oxycodone 1 mg and nefopam 1 mg bolus; and Ketorolac group treated with oxycodone 1 mg and ketorolac 1.5 mg bolus. After the operation, a blinded observer assessed the pain with a numeric rating scale (NRS), infused PCA dose and sedation score at 1, 4, 24, and 48 h, nausea, vomiting, headache, shivering, pruritus and delirium at 6, 24 and 48 h, and satisfaction at 48 h after the operation.

RESULTS

Nefopam group showed less nausea than Ketorolac group within 6 h after the operation. There were no significant differences in demographic data and other complications between both groups. At 48 h after operation, satisfaction and the infused PCA volumes of Nefopam group (34.0± 19.7 ml) showed no significant differences compared to Ketorolac group (30.7± 18.4 ml, P-value= 0.46).

CONCLUSION

Nefopam showed a similar efficacy and lower incidence of nausea within 6 h after the operation to that of ketorolac in PCA. Nefopam may be a useful analgesic drug for the opioid-based PCA after gynecologic surgery. Further evaluation of accurate equivalent dose of nefopam as well as pharmacokinetics of bolus administration is required.

Dosing of antirheumatic drugs in renal disease and dialysis

Many patients with rheumatic diseases have their management complicated by renal problems. Renal failure modifies the metabolism of many drugs, especially by retention. Questions often arise about the effects of renal failure on the handling of drugs commonly used in rheumatology. For which drugs must we be especially concerned about increased toxicity? Patients on chronic dialysis may also need a variety of drugs for rheumatic disease. How are our drugs dialyzed, and which of these can be safety used and how best to use them?Decisions about dosing of rheumatic drugs are often required for the patients with chronic renal insufficiency or on long-term dialysis, although many drugs have not been formally studied in these settings. Patients with renal insufficiency are excluded from most drug trials. Data for some of these drugs have to be extrapolated based on the information available about the pharmacokinetics of the drug.This review addresses dosing of commonly used drugs in rheumatology in patients with chronic renal insufficiency or failure. It is compiled from a MEDLINE search of papers dealing with renal handling of antirheumatic drugs and suggestions for dose adjustments for these drugs. Drugs reviewed include commonly used disease-modifying antirheumatic drugs (DMARDS), drugs used for treatment of gout, commonly used nonsteroidal antnflammatory drugs (NSAIDS) and the newer COX-2 inhibitors.

Intramuscular ketorolac injections in the athlete

Background:

Pain control is a factor in the sideline treatment of competitive athletes. Ketorolac injections by team physicians as a pain control measure are seemingly becoming more mainstream, although there have been very little data published on its use.

Hypothesis:

Intramuscular ketorolac injections are being used regularly by orthopaedic surgeons and primary care sports medicine physicians in their care of athletes.

Study Design:

Descriptive epidemiology study.

Methods:

A 19-question survey was generated online for physician members of the American Orthopaedic Society for Sports Medicine, the Arthroscopy Association of North America, and the American Medical Society for Sports Medicine. The survey link was e-mailed, with reminders sent every 1 to 2 weeks, and results were collected from April to June 2011.

Results:

The survey was e-mailed to 6950 physicians, with 1100 respondents completing it (60% orthopaedic surgeons, 40% nonsurgical sports medicine physicians). Approximately 49% use intramuscular ketorolac in the treatment of athletes, primarily at the collegiate and professional levels; 95.8% reported effective pain control after administration; 2.9% reported bleeding complications; and 1.9% reported kidney complications from its use.

Conclusion:

Intramuscular ketorolac injections are used by approximately half of all team physicians in their sideline treatment of competitive athletes.

Effect of Non-Steroidal Anti-Inflammatory Drugs on Bone Healing

Nonspecific and COX-2 selective nonsteroidal anti-inflammatory drugs (NSAIDs) function by inhibiting the cyclooxygenase isoenzymes and effectively reduce pain and inflammation attributed to acute or chronic musculoskeletal pathologies. However, use of NSAIDs as an analgesic is thought to negatively contribute to bone healing. This review strived to provide a thorough unbiased analysis of the current research conducted on animals and humans regarding NSAIDs and their effect on bone healing. Specifically, this review discusses the role of animal models, dosing regiments, and outcome parameters when examining discrepancies about NSAIDS and their effects on bone regeneration. The role of COX-2 in bone regeneration needs to be better defined in order to further elucidate the impact of NSAIDs on bone healing.

Ketorolac after congenital heart surgery: does it increase the risk of significant bleeding complications?

BACKGROUND

The routine use of ketorolac after congenital heart surgery in infants and children is limited by concerns for postoperative bleeding complications. The object of this study was to determine if the use of ketorolac is associated with an increased risk of significant postoperative bleeding after congenital heart surgery in infants and children.

METHODS

A retrospective chart review was performed. The exposure of interest was postoperative use of ketorolac after congenital heart surgery in infants and children. The outcome measured was postoperative bleeding requiring surgical exploration. The patients who received ketorolac were compared with an age- and diagnosis-matched comparison group who did not receive ketorolac.

RESULTS

Records of 842 infants and children who underwent congenital heart surgery between July 2001 and October 2002 were reviewed. 94 (11.1%) patients were treated with ketorolac postoperatively. The comparison group consisted of 94 matched subjects selected from the patients that did not receive ketorolac. The mean age of patient in the ketorolac group was 8.5 (+/-6.1) years. No (0%) patients in the ketorolac group and four (4.2%) patients in the nonketorolac group developed postoperative bleeding requiring surgical exploration. The relative risk for postoperative bleeding that required surgical exploration in the ketorolac group compared with the nonketorolac group was 0.2 (95% CI 0.02-1.67).

CONCLUSIONS

The use of ketorolac after congenital heart surgery in infants and children does not significantly increase the risk of bleeding complications requiring surgical exploration.

Ketorolac: Safe and Effective Analgesia for the Management of Renal Cortical Tumors With Partial Nephrectomy

PURPOSE

Ketorolac has demonstrated advantages as a supplement to opioid based analgesia in several surgical settings, including donor nephrectomy. To our knowledge there has been no published data to date on the use of ketorolac in patients undergoing partial nephrectomy. We compared analgesia with ketorolac and opioids to analgesia with opioids alone with regard to pain control, postoperative recovery and effects on renal function in patients with renal cortical tumors surgically managed by partial nephrectomy.

MATERIALS AND METHODS

Records for 154 patients treated with partial nephrectomy for renal cortical tumors were retrospectively analyzed. Clinicopathological variables examined were age, gender, medication use, comorbidity profile, operation side, estimated blood loss, hospital stay, operative duration, American Society of Anesthesiologists class, histopathology results, perioperative transfusion status, ischemia type (warm vs cold vs none), duration of renal artery cross clamping, tumor size and intraparenchymal location, pathological stage and perioperative complications. Postoperative duration to the initiation of solid diet, discontinuation of patient controlled analgesia and overall pain control were assessed. Serum creatinine was measured during the preoperative period, and at 1, 3 or greater and 30 or greater days postoperatively.

RESULTS

Patients who received ketorolac demonstrated superior postoperative recovery with an earlier return to solid diet and earlier discontinuation of patient controlled analgesia. Treatment groups were similar with respect to changes in serum creatinine, blood loss, transfusion rates and complication rates. Ketorolac was not associated with an increased risk of acute renal failure.

CONCLUSIONS

Ketorolac is a safe and effective supplement to opioid based analgesia for pain control after partial nephrectomy.

Ketorolac use in the national football league: prevalence, efficacy, and adverse events

Researchers who surveyed usage patterns, effectiveness, and possible adverse effects of ketorolac tromethamine among National Football League players found some common themes among the 31 teams that responded. Though isolated adverse events were noted, most team healthcare providers felt that ketorolac is effective and safe when the team physician directs its use.

Intra-muscular ketorolac administered as a supplemental analgesic for removal of impacted third molar teeth: a prospective study

BACKGROUND

Post-operative pain follows dentalveolar oral surgery. Ketorolac is a potent non-steroidal analgesic with moderate anti-inflammatory effects. The purpose of this study was to test whether a single supplementary dose of ketorolac reduced post-operative pain experienced by patients having third molar teeth removed.

METHODS

A prospective double-blind trial utilizing 30mg of ketorolac and a standard anaesthetic and surgical technique was performed on 65 female patients having impacted third molar teeth removed. Assessment was made by means of a patient questionnaire and visual analogue pain scales and subjected to statistical analysis.

RESULTS

There was a statistically significant difference confirming improved pain relief for patients receiving ketorolac 30mg at the early postoperative stage (two hours) but at later time intervals (four and six hours) there was no significant difference. Seventy two per cent of patients found ketorolac to be a satisfactory analgesic for postoperative pain. There were minimal side effects.

CONCLUSION

A single supplemental dose of ketorolac 30mg provides improved pain relief in the immediate post-operative phase following the removal of third molar teeth. Oral ketorolac can be recommended as a oral analgesic for post-operative pain, with minimal side effects.

Are selective COX-2 inhibitors nephrotoxic?

Nonsteroidal anti-inflammatory drugs are well-known culprits in the development of acute renal insufficiency in high-risk patients. The recent release of the selective cyclooxygenase-2 enzyme inhibitors for the treatment of inflammatory diseases and pain syndromes has been associated with a clear-cut decrease in adverse gastrointestinal effects. However, the nephrotoxic potential of these agents in patients with prostaglandin-dependent states and chronic renal impairment is unknown. Many clinicians commonly wonder if these agents can be safely prescribed to such high-risk patients. We present two cases of acute renal failure complicating the course of therapy with celecoxib in patients with chronic renal insufficiency.

The efficacy of sublingual hyoscyamine sulfate and intravenous ketorolac tromethamine in the relief of ureteral colic

A prospective, randomized, open-label, single-dose study was conducted in an emergency department (ED) of a tertiary care teaching hospital to evaluate the efficacy of hyoscyamine sulfate as compared to ketorolac tromethamine for the reduction of pain from ureteral colic in the ED. Patients were included if they were at least 18 years of age and presented to the ED with an initial history and physical examination consistent with ureteral colic. Ureteral calculi were confirmed by ultrasound or intravenous urogram. Consecutive patients were randomized to either a single sublingual dose of 0.125 mg of hyoscyamine sulfate or a single intravenous dose of 30 mg of ketorolac tromethamine given over 1 minute. After 30 minutes, if analgesia was inadequate, patients were given rescue medication. Baseline pain scores were obtained using a horizontal, 100-mm visual analog scale. Additional pain scores were obtained at 10-minute intervals for 30 minutes. Upon completion of the study, both patients and physicians completed a global assessment score questionnaire. Fifty-four evaluable patients were randomized. Demographics and baseline pain scores were similar for each group. Decreasing trends in pain over time were observed for both treatment groups, with significantly greater pain reduction observed with ketorolac tromethamine as compared to hyoscyamine sulfate. Global evaluations of pain relief revealed better results in the ketorolac tromethamine group than in the hyoscyamine sulfate group, although this result was not statistically significant.

Clinical implications of ketorolac for postoperative analgesia

Ketorolac is the only nonsteroidal anti-inflammatory drug (NSAID) in widespread clinical use that is available in an injectable form. Though similar to aspirin and ibuprofen, it is much more potent. In fact, it is potent enough to be useful for postsurgical pain either alone or in combination with other pain relief strategies. For many types of pain, ketorolac is comparable in potency with opioids though the mechanism by which it relieves pain is significantly different. Ketorolac has a much longer duration than morphine or meperidine but has a slower onset. Though we sometimes perceive NSAIDs as almost harmless, ketorolac is a potent drug and, like other potent drugs, has the potential to produce potent adverse effects including organ disfunction and allergic reaction. Risk factors for these adverse effects are well understood, allowing the clinician to plan the ketorolac use safely. Well planned patient selection and ketorolac administration can improve patient care by reducing opioid side effects and improving analgesia while speeding patient recovery and PACU discharge times.

Drug administration in patients with renal insufficiency. Minimising renal and extrarenal toxicity

Renal insufficiency has been associated with an increased risk of adverse effects with many classes of medications. The risk of some, but not all, adverse effects has been linked to the patient's degree of residual renal function. This may be the result of inappropriate individualisation of those agents that are primarily eliminated by the kidney, or an alteration in the pharmacodynamic response as a result of renal insufficiency. The pathophysiological mechanism responsible for alterations in drug disposition, especially metabolism and renal excretion, is the accumulation of uraemic toxins that may modulate cytochrome P450 enzyme activity and decrease glomerular filtration as well as tubular secretion. The general principles to enhance the safety of drug therapy in patients with renal insufficiency include knowledge of the potential toxicities and interactions of the therapeutic agent, consideration of possible alternatives therapies and individualisation of drug therapy based on patient level of renal function. Although optimisation of the desired therapeutic outcomes are of paramount importance, additional pharmacotherapeutic issues for patients with reduced renal function are the prevention or minimisation of future acute or chronic nephrotoxic insults, as well as the severity and occurrence of adverse effects on other organ systems. Risk factors for the development of nephrotoxicity for selected high-risk therapies (e.g. aminoglycosides, nonsteroidal anti-inflammatory drugs, ACE inhibitors and radiographic contrast media) are quite similar and include pre-existing renal insufficiency, concomitant administration of other nephrotoxins, volume depletion and concomitant hepatic disease or congestive heart failure. Investigations of prophylactic approaches to enhance the safety of these agents in patients with renal insufficiency have yielded inconsistent outcomes. Hydration with saline prior to drug exposure has given the most consistent benefit, while sodium loading and use of pharmacological interventions [e.g. furosemide (frusemide) dopomine/dobutamine, calcium antagonists and mannitol] have resulted in limited success. The mechanisms responsible for altered dynamic responses of some agents (benzodiazepines, theophylline, digoxin and loop diuretics) in renally compromised patients include enhanced receptor sensitivity secondary to the accumulation of endogenous uraemic toxins and competition for secretion to the renal tubular site of action. Application of the pharmacotherapeutic principles discussed into clinical practice will hopefully enhance the safety of these agents and optimise patient outcomes.

Ketorolac. A reappraisal of its pharmacodynamic and pharmacokinetic properties and therapeutic use in pain management

Ketorolac is a nonsteroidal anti-inflammatory drug (NSAID) with strong analgesic activity. The analgesic efficacy of ketorolac has been extensively evaluated in the postoperative setting, in both hospital inpatients and outpatients, and in patients with various other acute pain states. After major abdominal, orthopaedic or gynaecological surgery or ambulatory laparoscopic or gynaecological procedures, ketorolac provides relief from mild to severe pain in the majority of patients and has similar analgesic efficacy to that of standard dosages of morphine and pethidine (meperidine) as well as less frequently used opioids and other NSAIDs. The analgesic effect of ketorolac may be slightly delayed but often persists for longer than that of opioids. Combined therapy with ketorolac and an opioid results in a 25 to 50% reduction in opioid requirements, and in some patients this is accompanied by a concomitant decrease in opioid-induced adverse events, more rapid return to normal gastrointestinal function and shorter stay in hospital. In children undergoing myringotomy, hernia repair, tonsillectomy, or other surgery associated with mild to moderate pain, ketorolac provides comparable analgesia to morphine, pethidine or paracetamol (acetaminophen). In the emergency department, ketorolac attenuates moderate to severe pain in patients with renal colic, migraine headache, musculoskeletal pain or sickle cell crisis and is usually as effective as frequently used opioids, such as morphine and pethidine, and other NSAIDs and analgesics. Subcutaneous administration of ketorolac reduces pain in patients with cancer and seems particularly beneficial in pain resulting from bone metastases. The acquisition cost of ketorolac is greater than that of morphine or pethidine; however, in a small number of studies, the higher cost of ketorolac was offset when treatment with ketorolac resulted in a reduced hospital stay compared with alternative opioid therapy. The tolerability profile of ketorolac parallels that of other NSAIDs; most clinically important adverse events affect the gastrointestinal tract and/or renal or haematological function. The incidence of serious or fatal adverse events reported with ketorolac has decreased since revision of dosage guidelines. Results from a large retrospective postmarketing surveillance study in more than 20,000 patients demonstrated that the overall risk of gastrointestinal or operative site bleeding related to parenteral ketorolac therapy was only slightly higher than with opioids. However, the risk increased markedly when high dosages were used for more than 5 days, especially in the elderly. Acute renal failure may occur after treatment with ketorolac but is usually reversible on drug discontinuation. In common with other NSAIDs, ketorolac has also been implicated in allergic or hypersensitivity reactions. In summary, ketorolac is a strong analgesic with a tolerability profile which resembles that of other NSAIDs. When used in accordance with current dosage guidelines, this drug provides a useful alternative, or adjuvant, to opioids in patients with moderate to severe pain.

Management of acute renal failure in the elderly. Treatment options

Renal changes that occur with aging mainly consist of impairment in the ability to concentrate urine and to conserve sodium and water. These physiological changes increase the risk of volume depletion and the prerenal type of acute renal failure (ARF) in elderly people. Bladder outlet obstruction caused by benign prostatic hypertrophy is a common cause of ARF in elderly men. Another frequent cause of ARF in the elderly is drug-induced nephropathy. Nonsteroidal anti-inflammatory drugs (NSAIDs) and antibiotics are most often implicated in the development of ARF in the elderly. However, considering the high usage of these drugs, the incidence of drug-induced nephropathy is relatively small. NSAIDs are more likely to cause ARF in patients with congestive heart failure, chronic renal disease (including diabetic nephropathy) or chronic liver disease than in otherwise healthy individuals. NSAID-induced ARF is often of the prerenal type, but may be caused by acute interstitial nephritis (AIN). The presence of heavy proteinuria or nephrotic syndrome differentiates NSAID-induced AIN from AIN caused by other drugs. Antibiotics, especially semisynthetic penicillins, more commonly give rise to AIN associated with peripheral blood eosinophilia and eosinophiluria than NSAIDs. Ciprofloxacin is increasingly reported to cause AIN. Fever commonly accompanies AIN, especially when induced by antibiotics. Aminoglycosides produce ARF by inducing acute tubular necrosis (ATN), which results from the excessive accumulation of myeloid bodies in the tubules. In all cases of ARF it is essential to obtain a good history, to perform a through physical examination, with particular attention to skin turgor, and to measure blood pressure, pulse rate (supine and upright), urinary electrolyte and creatinine levels. Fractional excretion of sodium and the urine:plasma creatinine ratio are reliable indices that distinguish prerenal ARF from ATN. A prompt response to fluid challenge, with an increase in urine output and urinary sodium excretion, and a rapid decrease in blood urea nitrogen, constitutes strong evidence for prerenal ARF. However, these indices are unreliable when prerenal ARF has progressed to ATN or when ARF has an obstructive pattern to begin with. In all cases of ARF, especially in elderly men, urinary tract obstruction should be suspected unless the history is otherwise clear cut. Ultrasound of the kidneys and bladder is a simple, non-invasive and meaningful test that can be used to rule out obstructive causes of ARF. If obstruction is the cause of ARF, ultrasound will be positive; in contrast, urinary obstruction is very unlikely if ultrasound findings are normal in a patient who has been oliguric or anuric for 48 hours or more. Similarly, acute glomerulonephritis, including rapidly progressive glomerulonephritis, should be suspected when ARF is associated with heavy proteinuria. In such instances, percutaneous renal biopsy is essential to document the diagnosis. It is of utmost importance to establish whether ARF is of prerenal or postrenal type, both of which are potentially fully reversible. In contrast, patients with ATN or rapidly progressive glomerulonephritis may not recover, or may only partially recover, their renal function. Haemodialysis and nutritional support are common measures for patients with severe ATN and a highly catabolic state. Corticosteroids and immunosuppressive therapy should be instituted for rapidly progressive glomerulonephritis, in addition to haemodialysis. haemodiafiltration instead of haemodialysis is recommended for patients who are haemodynamically unstable [i.e., with a persistently low blood pressure (systolic < or = 100 mm Hg)]. Haemodiafiltration has been shown to improve acid-base balance and uraemia better than standard haemodialysis. However, despite dialysis, mortality in patients with ARF associated with ischaemic ATN remains high.