Hypercalcaemia and acute interstitial nephritis associated with omeprazole therapy

Rare Causes of Hypercalcemia: 2021 Update

CONTEXT

Primary hyperparathyroidism and malignancy are the etiologies in 90% of cases of hypercalcemia. When these entities are not the etiology of hypercalcemia, uncommon conditions need to be considered. In 2005, Jacobs and Bilezikian published a clinical review of rare causes of hypercalcemia, focusing on mechanisms and pathophysiology. This review is an updated synopsis of rare causes of hypercalcemia, extending the observations of the original article.

EVIDENCE ACQUISITION

Articles reporting rare associations between hypercalcemia and unusual conditions were identified through a comprehensive extensive PubMed-based search using the search terms "hypercalcemia" and "etiology," as well as examining the references in the identified case reports. We categorized the reports by adults vs pediatric and further categorized the adult reports based on etiology. Some included reports lacked definitive assessment of etiology and are reported as unknown mechanism with discussion of likely etiology.

EVIDENCE SYNTHESIS

There is a growing understanding of the breadth of unusual causes of hypercalcemia. When the cause of hypercalcemia is elusive, a focus on mechanism and review of prior reported cases is key to successful determination of the etiology.

CONCLUSIONS

The ever-expanding reports of patients with rare and even unknown mechanisms of hypercalcemia illustrate the need for continued investigation into the complexities of human calcium metabolism.

Proton Pump Inhibitors and Kidney Disease - GI Upset for the Nephrologist?

Widely regarded as safe and effective, proton pump inhibitors (PPIs) are among the most commonly used medications in the world today. However, a spate of observational studies suggest an association between PPI use and adverse events, including infection, bone fracture, and dementia. This review details evidence linking the use of PPI therapy to the development of kidney disease, including early case reports of acute interstitial nephritis and subsequent large observational studies of acute kidney injury (AKI), chronic kidney disease (CKD), and end-stage renal disease (ESRD). The majority of studies showed higher risk of kidney outcomes among persons prescribed PPI medications, with effect sizes that were slightly higher for AKI (∼2-3-fold) compared to CKD and ESRD (1.2-1.8-fold). Although observational pharmaco-epidemiology studies are limited by the possibility of residual confounding and confounding by indication, many of the described studies conducted rigorous sensitivity analyses aimed at minimizing these biases, including new-user design, comparison to similar agents (e.g., histamine₂ receptor antagonists), and evaluation for a dose-response, with robust results. Given the widespread use of PPIs, even a small effect on kidney outcomes could result in large public health burden. Timely cessation of PPI therapy when there is no clear indication for use might reduce the population burden of kidney disease.

Systematic review: Proton pump inhibitor-associated acute interstitial nephritis

BACKGROUND

A number of recent case reports and case series suggest that proton pump inhibitors may cause acute interstitial nephritis.

AIM

To establish the nature of the relationship (cause or association) between proton pump inhibitor use and development of interstitial nephritis.

DATA COLLECTION

Two researchers independently searched electronic databases (MEDLINE, EMBASE, GOOGLE, LILACS, COCHRANE) for articles from 1970 to 2006, including all study designs, populations and languages. Two independent reviewers assessed study quality and collected the data.

SELECTION CRITERIA

absence of baseline renal failure, development of interstitial nephritis after proton pump inhibitor exposure, nephritis confirmed by creatinine plus either renal biopsy or recurrence upon reinitiating proton pump inhibitor.

RESULTS

Sixty four cases (60% females, mean age 78 years) of proton pump inhibitor-associated interstitial nephritis were found, 60 included in this review (59 confirmed by renal biopsy, one by recurrence upon reinitiating proton pump inhibitor). The most common symptoms were non-specific. The mean proton pump inhibitor treatment duration before diagnosing nephritis was 13 weeks, average recovery time was 35.5 weeks, one patient required permanent dialysis, there were no deaths.

CONCLUSION

Proton pump inhibitor-related interstitial nephritis is rare, idiosyncratic and difficult to predict. It requires a high level of clinical suspicion. While there is not sufficient evidence to establish a causal relationship with certainty, there does appear to be a low-prevalence association.

Proton pump inhibitors and acute interstitial nephritis: Report and analysis of 15 cases

AIM

Although proton pump inhibitors (PPI) are usually safe and effective therapeutic agents, serious adverse effects can occur. The aim of the present study was to report and analyse the clinical features of 15 patients with acute interstitial nephritis (AIN) and acute renal failure from PPI that were referred to renal services in Auckland over a period of 3 years.

METHODS

The clinical presentation, therapeutic drugs, demographic details and renal outcome of the patients were considered. The population at risk and total PPI exposure were able to be defined. The diagnosis of AIN was made by renal biopsy in 12 cases. In all patients, the time-course of drug exposure and improvement of renal function on withdrawal suggested PPI were causal.

RESULTS

The median patient age was 78 years. The mean baseline serum creatinine level was 83 micromol/L, peak level 392 micromol/L, and recovery level 139 micromol/L. The erythrocyte sedimentation rate (ESR) and C-reactive protein were elevated at the time of diagnosis in the 11 and 12 patients, respectively, where this information was collected (ESR mean 85 mm/h, and C-reactive protein mean 81 mg/L). AIN occurred at 8 per 100 000 patient years (95% confidence level 2.6-18.7 per 100 000 patient years). Although four patients presented with an acute systemic allergic reaction, 11 were asymptomatic with an insidious development of renal failure.

CONCLUSION

PPI are now the most commonly identified cause of AIN in the Auckland area. Recovery occurs after withdrawal of the drug but is often incomplete. Early diagnosis may be facilitated by clinician awareness of the insidious onset of renal failure, and an elevated erythrocyte sedimentation rate and C-reactive protein.

Proton pump inhibitors and acute interstitial nephritis

BACKGROUND & AIMS

Proton pump inhibitors (PPIs) are a widely prescribed class of drugs, and their usage worldwide is increasing. Although well-tolerated, there have been case reports and a recent case series implicating these drugs in acute interstitial nephritis (AIN) and progression to acute renal failure (ARF). The aim of this study was to investigate how widespread this complication is in Australia, to identify which PPIs are implicated, and to establish whether PPI-induced AIN is a class effect.

METHODS

We undertook a retrospective case review of potential cases at 2 teaching hospitals and a review of registry data from the Therapeutic Goods Administration of Australia (TGA). Parameters sought included the drug implicated, concurrent medications, symptoms, signs, serum creatinine, and time of onset after prescription.

RESULTS

We identified 18 cases of biopsy-proven PPI-induced AIN causing ARF in the retrospective case review, which is the largest hospital-based case series to date. The TGA registry data identified an additional 31 cases of "biopsy proven interstitial nephritis." An additional 10 cases of "suspected interstitial nephritis," 20 cases of "unclassified acute renal failure," and 26 cases of "renal impairment" were also identified. All 5 commercially available PPIs were implicated in these cases.

CONCLUSION

With the ever more widespread use of this class of medications, PPI-induced AIN is likely to become more frequent. There is now evidence to incriminate all the commercially available PPIs, suggesting there is a class effect. Failure to recognize this entity might have catastrophic long-term consequences including chronic kidney disease. Increased awareness might facilitate more rapid diagnosis and management of this potentially reversible condition.

Clinical review: Rare causes of hypercalcemia

CONTEXT

Although hypercalcemia is usually caused by primary hyperparathyroidism or malignancy, a number of other conditions can be important to consider. This review considers unusual causes of hypercalcemia that are generally not found in reviews on this subject.

EVIDENCE ACQUISITION

Articles describing rarely reported associations between hypercalcemia and unusual causes were identified through a computer search of the terms hypercalcemia/etiology and through the references listed in those articles. We grouped the 58 different reports into categories defined by a presumed etiology: increased levels of 1,25-dihydroxyvitamin D or PTHrP, occult milk-alkali syndrome, and undefined mechanisms. Reports in infants and children are listed separately, as are reports of pseudohypercalcemia, situations that are not truly hypercalcemic because the ionized calcium is normal.

EVIDENCE SYNTHESIS

In some situations, as this review points out, a number of unusual causes of hypercalcemia are important to consider. The search for an elusive cause of hypercalcemia is best accomplished by the most likely potential mechanism. An orderly search in this manner is likely to reveal the underlying cause.

CONCLUSIONS

That so many patients have been described with rare and usually poorly understood causes of hypercalcemia highlights our incomplete understanding of calcium metabolism in humans and suggests additional areas in which directed clinical investigation might improve our knowledge of the normal metabolism of calcium.

Rabeprazole-induced acute interstitial nephritis. Case Report

Acute interstitial nephritis is an uncommon but important cause of acute renal failure. Proton pump inhibitors are now thought to be the most common class of drugs implicated in drug-induced acute interstitial nephritis. This is the first reported case of rabeprazole-induced acute interstitial nephritis.

Drug-induced tubulo-interstitial nephritis secondary to proton pump inhibitors: experience from a single UK renal unit

BACKGROUND

Acute tubulo-interstitial nephritis (TIN) is an important cause of acute renal failure, and is often caused by hypersensitivity to drugs. The aim of this study was to determine the aetiology of interstitial nephritis among an unselected cohort of patients, and to identify those drugs commonly implicated.

METHODS

A single-centre retrospective analysis was carried out of renal biopsy results from 296 consecutive patients between 1995 and 1999.

RESULTS

Acute TIN was identified in 24 (8.1%) biopsies. Eight out of 14 cases with presumed drug-related TIN could be attributed to the proton pump inhibitors omeprazole and lansoprazole. The two cases of lansoprazole-associated TIN are the first to be reported with this drug. The presentation and favourable response to treatment of these patients are described.

CONCLUSION

Drugs are the most common cause of interstitial nephritis in the population studied. Those drugs most commonly associated with interstitial nephritis were the proton pump inhibitors omeprazole and lansoprazole.