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Deep Dives

Platinum & the proximal tubule

Cisplatin acute tubular necrosis & hypomagnesemia

The drug that cures testicular cancer poisons its own portal of entry — pumped into the kidney's S3 tubule by OCT2, cisplatin necroses the proximal tubule and, downstream, silences the distal magnesium channel, leaving patients wasting magnesium long after the last dose.

~1 in 3
Develop AKI after cisplatin31.5% of 821 adults across tumor types had acute kidney injury within 30 days of the first cycle
1969
Platinum's antitumor power revealedRosenberg's Nature report turned a bacterial curiosity into a cancer drug — and into nephrology's archetypal tubular toxin
OR 0.24
Magnesium's protective oddsMeta-analysis of 15 studies (1841 patients): magnesium supplementation cut cisplatin AKI odds by about 76%
23 / 44
Hypomagnesemia on cisplatinSchilsky's 1979 series first tied cisplatin to inappropriate renal magnesium wasting
56 vs 79
Mannitol backfired (mL/min CrCl)In a randomized trial, adding mannitol to saline left worse creatinine clearance than saline alone
Acute Tubular NecrosisElectrolyte DisturbanceCisplatinCarboplatinOxaliplatin

Teaching case · illustrative composite, not a real patient

A 58-year-old man with locally advanced head and neck squamous cell carcinoma receives his second cycle of high-dose cisplatin (100 mg/m²) with concurrent radiotherapy. He presents on about day 8 with fatigue, muscle cramps, and mild nausea. Labs show a nonoliguric rise in serum creatinine (roughly a 40% increase from baseline), magnesium 1.0 mg/dL, potassium 3.0 mmol/L, and mild hypocalcemia; urine studies show renal magnesium wasting with an inappropriately high fractional excretion of magnesium.

He had received isotonic saline hydration but no magnesium supplementation. The hypokalemia and hypocalcemia stay refractory to potassium and calcium replacement until magnesium is aggressively repleted, after which they correct. Mannitol is deliberately not added. Creatinine partially recovers over the next two weeks but settles at a new, slightly reduced baseline eGFR. Magnesium continues to run low for weeks, requiring ongoing oral (and intermittent IV) supplementation between cycles; subsequent cycles use pre-emptive magnesium loading and careful volume expansion.

Teaching point — Cisplatin injures the kidney at two distinct sites: OCT2-driven uptake concentrates drug in the S3 proximal segment causing acute tubular necrosis, while downstream suppression of distal TRPM6 causes renal magnesium wasting. The hypomagnesemia is often the more persistent problem and drives refractory hypokalemia and hypocalcemia — correct magnesium first. Volume-expand with isotonic saline (not mannitol), supplement magnesium pre-emptively, and keep monitoring magnesium and eGFR for weeks to months after the last dose.

01

How it happens

The pathophysiology as a cascade — select a step to follow the mechanism.

See it happen

§Mechanism, step by step

How cisplatin injures the proximal tubule

The archetypal nephrotoxin traces a defined path: filtration, active transporter uptake, mitochondrial catastrophe, and downstream electrolyte wasting. Scroll to follow the lesion from the S3 segment to the distal tubule.

How cisplatin injures the nephronA schematic nephron with a magnified proximal tubule epithelial cell. Filtered cisplatin is taken up across the basolateral membrane by OCT2 and organic anion transporters, injures S3 mitochondria to cause acute tubular necrosis, and downstream causes distal magnesium wasting.Mg²⁺Mg²⁺Mg²⁺OCT2OATPtPtGlomerulusProximaltubule (S1–S3)Loop of HenleDistal tubuleCollecting ductS3 epithelial cellBasolateral membraneLumen
Schematic · not to scale
02

How we learned it

  1. 1967

    Rosenberg observes that platinum electrolysis products halt cell division in E. coli, causing filamentous growth.

    The serendipitous discovery that a platinum compound has potent biological activity — the seed of cisplatin as a drug.

    PMID 5335970
  2. 1969

    Rosenberg and colleagues report in Nature that cis-platinum compounds cause dramatic regression of transplanted mouse tumors.

    Established platinum as a potent antitumor agent and launched cisplatin's path to the clinic — along with its dose-limiting kidney problem.

    PMID 5782119
  3. 1977

    Hayes and Cvitkovic show mannitol-induced osmotic diuresis blunts cisplatin's renal toxicity, enabling high-dose therapy.

    The Cvitkovic-era breakthrough that made cisplatin clinically usable — hydration/diuresis converted a nephrotoxin into a curative drug.

    PMID 856437
  4. 1978

    Cisplatin receives FDA approval for testicular and ovarian cancer.

    Cemented cisplatin in oncology and made its nephrotoxicity and magnesium wasting an everyday clinical management problem.

  5. 1979

    Schilsky and Anderson describe hypomagnesemia and inappropriate renal magnesium wasting in cisplatin patients.

    First systematic description of the distinct distal-tubule magnesium-wasting syndrome, separate from the proximal AKI.

    PMID 375794
  6. 2003

    Santoso randomized trial finds adding mannitol to saline yields worse creatinine clearance than saline alone.

    Challenged reflexive forced diuresis — isotonic saline, not mannitol, is the safe hydration backbone.

    PMID 12719883
  7. 2005

    Ciarimboli identifies human OCT2 (SLC22A2) as the critical basolateral transporter carrying cisplatin into proximal tubule cells.

    Explained cisplatin's organ-specific toxicity mechanistically and pointed to transporter competition as a renoprotective strategy.

    PMID 16314463
  8. 2009

    Filipski shows Oct1/Oct2-null mice are protected and links the SLC22A2 SNP rs316019 to reduced nephrotoxicity in patients.

    Nailed OCT2 as the pharmacogenetic gatekeeper of cisplatin nephrotoxicity, bridging bench to bedside.

    PMID 19625999
  9. 2013

    Ledeganck demonstrates cisplatin downregulates distal-tubule EGF and the TRPM6 magnesium channel in rats.

    Provided the molecular mechanism of cisplatin's distal magnesium wasting, decades after Schilsky's clinical description.

    PMID 23457647
  10. 2016

    Latcha reports the largest long-term outcome study (821 adults): AKI is common but ESRD is rare.

    Reframed cisplatin nephrotoxicity as mostly small, permanent eGFR loss rather than dialysis-requiring failure.

    PMID 27073199
  11. 2020

    Song shows the SGLT2 inhibitor canagliflozin reduces renal cisplatin uptake and protects mice without blunting anticancer effect.

    Opened a current renoprotection frontier — repurposing SGLT2 inhibitors against cisplatin AKI and magnesium wasting.

    PMID 32150448
03

The landmark studies

Preclinical (transplanted mouse tumor models)

Platinum compounds: a new class of potent antitumour agents

Rosenberg B, et al. · Nature 1969 · PMID 5782119

cis-Platinum(II) diamminedichloride produced dramatic regression of transplanted mouse tumors, defining platinum as a potent antitumor agent and launching cisplatin's clinical development.

Marked regression of Sarcoma 180 and L1210 leukemia in mice; the foundational report that made cisplatin a drug.

Clinical trial (60 patients enrolled, 51 evaluable)

High dose cis-platinum diammine dichloride: amelioration of renal toxicity by mannitol diuresis

Hayes DM, Cvitkovic E, et al. · Cancer 1977 · PMID 856437

Concurrent mannitol-induced osmotic diuresis allowed high-dose cisplatin to be delivered with renal toxicity limited mostly to transient creatinine elevation — the practice that made high-dose cisplatin feasible.

60 heavily pretreated patients; doses 3–5 mg/kg; overall response rate 42%; renal injury reduced to transient creatinine rises in most, with dose-limiting renal toxicity only at 5 mg/kg.

Case series (retrospective review of 44 + prospective follow-up of 7 patients)

Hypomagnesemia and renal magnesium wasting in patients receiving cisplatin

Schilsky RL, Anderson T. · Annals of Internal Medicine 1979 · PMID 375794

Cisplatin induces an intrinsic renal tubular defect in magnesium conservation, producing symptomatic hypomagnesemia distinct from its proximal azotemia.

Hypomagnesemia in 23 of 44 evaluable patients; inappropriate renal magnesium wasting documented in 4; 2 hospitalized for symptomatic magnesium deficiency.

In vitro (HEK293 transfectants + isolated human proximal tubules and hepatocytes)

Cisplatin nephrotoxicity is critically mediated via the human organic cation transporter 2

Ciarimboli G, et al. · American Journal of Pathology 2005 · PMID 16314463

Human OCT2 (hOCT2) is the critical basolateral transporter for cisplatin uptake into proximal tubule cells, explaining its organ-specific toxicity; competing at hOCT2 prevents cisplatin-induced apoptosis.

Cisplatin 100 µmol/L inhibited transport via hOCT2 but not hepatic hOCT1; co-incubation with the hOCT2 substrate cimetidine (100 µmol/L) completely suppressed cisplatin-induced apoptosis.

Knockout-mouse experiments + human pharmacogenetic association

Contribution of organic cation transporter 2 (OCT2) to cisplatin-induced nephrotoxicity

Filipski KK, et al. · Clinical Pharmacology & Therapeutics 2009 · PMID 19625999

Oct1/Oct2-deficient mice are protected from severe cisplatin tubular damage, and a nonsynonymous SLC22A2 SNP (rs316019) is associated with reduced cisplatin nephrotoxicity in patients — establishing OCT2 as the pharmacogenetic gatekeeper.

Dose-limiting nephrotoxicity occurs in about one-third of patients despite prophylaxis; Oct1/Oct2 deletion impaired urinary cisplatin excretion (without changing plasma levels) and prevented severe renal tubular damage.

Rat model (2.5 mg/kg/week × 3) with RT-PCR and Western blot

The TRPM6/EGF pathway is downregulated in a rat model of cisplatin nephrotoxicity

Ledeganck KJ, et al. · PLoS One 2013 · PMID 23457647

Cisplatin downregulates distal-tubule EGF and the magnesium channel TRPM6, impairing distal Mg²⁺ reabsorption — the molecular basis of cisplatin's renal magnesium wasting.

Fractional excretion of Mg²⁺ significantly increased after cisplatin; renal TRPM6 and EGF mRNA significantly decreased, while TRPM7 and claudin-16 remained stable.

Retrospective cohort (821 adults, multiple tumor types, mean 6-year follow-up)

Long-Term Renal Outcomes after Cisplatin Treatment

Latcha S, et al. · Clinical Journal of the American Society of Nephrology (CJASN) 2016 · PMID 27073199

AKI after cisplatin is common but progression to end-stage disease is rare; most patients sustain small, permanent declines in eGFR, and older age raises AKI risk.

AKI in 31.5%; median initial eGFR decline ~10 mL/min/1.73 m²; <3% ever reached eGFR <29 and none required dialysis; age >66 vs <25 carried an OR of 2.96 (95% CI 1.4–6.1) for AKI.

04

What the data says now

How disproportionately each agent's FAERS reports name these phenotypes vs. all other drugs (reporting odds ratio; significant signals only, 95% CI lower bound > 1; as of 2026-07-10). A reporting signal, not incidence or proven causation.

Per-agent FAERS reporting odds ratio for each injury phenotype in this syndrome.
AgentATNLYTE
CisplatinCisplatin, Acute Tubular Necrosis: ROR 5.19, 182 reportsCisplatin, Electrolyte Disturbance: ROR 5.41, 3,562 reports
CarboplatinCarboplatin, Acute Tubular Necrosis: ROR 4.91, 275 reportsCarboplatin, Electrolyte Disturbance: ROR 3.72, 4,000 reports
OxaliplatinOxaliplatin, Acute Tubular Necrosis: ROR 1.94, 65 reportsOxaliplatin, Electrolyte Disturbance: ROR 3.32, 2,116 reports
31.5%

Acute kidney injury after cisplatin

821 adults across tumor types, ≥5-year survivors (retrospective cohort); AKI within 30 days of first cycle

PMID 27073199
~20–40% of exposed patients

Cisplatin-induced AKI (pooled estimate)

Adults receiving cisplatin, despite standard prophylaxis (systematic review/meta-analysis)

PMID 31429065
23 of 44 patients (~52%)

Hypomagnesemia on cisplatin

Patients receiving cisplatin chemotherapy (case series)

PMID 375794
~one-third (≈33%)

Nephrotoxicity despite intensive prophylaxis

Patients on cisplatin with intensive prophylactic hydration

PMID 19625999
<3% reached eGFR <29; 0% required dialysis

Progression to advanced CKD / dialysis long-term

821 adults, mean 6-year follow-up after cisplatin

PMID 27073199
05

How it's managed

  1. 1

    Isotonic (0.9%) saline hydration / volume expansion

    Vigorous isotonic saline before and after cisplatin is the cornerstone renoprotective measure, diluting tubular drug concentration and maintaining urine flow — the practice descended from the Cvitkovic-era diuresis studies.

    Established standard of care; historical foundation · PMID 856437

  2. 2

    Magnesium supplementation

    Adding magnesium to hydration both treats the wasting syndrome and independently lowers AKI risk; pooled observational data show a large protective effect.

    Meta-analysis: AKI odds ratio 0.24 (95% CI 0.19–0.32) across 15 studies / 1841 patients · PMID 31429065

  3. 3

    Magnesium supplementation (confirmatory meta-analysis)

    A second independent meta-analysis of magnesium given during hydration found consistent protection against cisplatin-induced nephrotoxicity.

    Meta-analysis: AKI odds ratio 0.22 (95% CI 0.14–0.35), 11 studies · PMID 37530867

  4. 4

    Avoid routine mannitol / aggressive forced diuresis

    Adding mannitol to saline did not help and was associated with worse creatinine clearance than saline alone; diuretics are not a substitute for volume expansion.

    Randomized trial (n=49): post-cisplatin CrCl 56.4 (saline+mannitol) vs 79.1 mL/min (saline alone), P=0.02 · PMID 12719883

  5. 5

    Limit cumulative dose, fractionate, and mitigate host risk

    Cumulative cisplatin dose and older age drive long-term eGFR loss; dose-capping, fractionated dosing, avoiding concurrent nephrotoxins, and monitoring eGFR reduce permanent injury.

    Large cohort: higher cumulative dose and age >66 (OR 2.96) associated with AKI/eGFR decline · PMID 27073199

  6. 6

    Emerging: SGLT2 inhibitors and OCT2-directed strategies

    Preclinically, canagliflozin cuts renal cisplatin uptake and protects tubules without blunting anticancer efficacy; OCT2 substrate competition (e.g., cimetidine) and amiloride/SGLT2 inhibitors are being explored for the magnesium wasting — currently investigational/off-label.

    Preclinical (mouse) renoprotection signal; off-label clinical case reports/reviews · PMID 32150448

06

What the guidelines say

Society and consensus recommendations addressing this syndrome, each with its key recommendation quoted verbatim.

ADQIThe nephrotoxic effects of anti-cancer therapies: consensus report of the 34th Acute Disease Quality Initiative workgroupNat Rev Nephrol 2026 · PMID 41361704Provides expert-based statements (modified Delphi) on preventing and managing cisplatin/platinum-associated AKI, including isotonic IV hydration, attention to volume status and concomitant nephrotoxins, and incorporates evidence that IV magnesium supplementation may reduce cisplatin-associated AKI; emphasizes risk stratification and standardized AKI definitions.ADQIConventional cytotoxic chemotherapy-associated nephrotoxicity: consensus report of the 34th Acute Disease Quality Initiative (ADQI) WorkgroupKidney Int 2026 · PMID 41881107Cisplatin is identified as a leading cytotoxic nephrotoxin; the workgroup details preventive measures (adequate isotonic hydration, correction of volume depletion, avoidance of concurrent nephrotoxins, attention to electrolyte/magnesium wasting) and management of cisplatin-associated AKI, with a research agenda for knowledge gaps.Expert ConsensusThe Prevention of Cisplatin-Induced Nephrotoxicity: A General Consensus Statement of a Group of Oncologist-Hematologists, Adult and Pediatric Nephrologists, Radiation Oncologists, Clinical Pathologists, Clinical Pharmacologists, and Renal Physiologists on Cisplatin Therapy in Cancer PatientsInt J Prev Med 2022 · PMID 35392316Consensus on modifiable factors for cisplatin nephrotoxicity prevention, addressing hydration methods, magnesium supplementation, dextrose, avoidance of NSAIDs and renin-angiotensin system inhibitors and contrast agents around cisplatin, GFR assessment, antioxidants, and patient factors (age, sex, female hormones).KDIGOKDIGO Controversies Conference on onco-nephrology: understanding kidney impairment and solid-organ malignancies, and managing kidney cancerKidney Int 2020 · PMID 33126977Identifies platinum compounds (especially cisplatin) as leading cytotoxic causes of acute tubular injury, AKI, and electrolyte/magnesium wasting; calls for interdisciplinary onco-nephrology care, accurate GFR estimation, and individualized drug dosing in patients with reduced kidney function.
07

At the bedside

Magnesium wasting here is cumulative and often silent until it's severe. Grade the level to gauge urgency and route — oral repletion rarely keeps pace once IV territory is reached.

Magnesium grade & repletion

CTCAE v5.0

Enter a serum magnesium level for its CTCAE grade and a directed-repletion frame. Drug-induced renal magnesium wasting (anti-EGFR antibodies, platinums) is cumulative — grade guides urgency and route.

Enter a level to see the CTCAE grade and repletion frame.

Educational aid only — not medical advice. Grades per NCI CTCAE v5.0; repletion route and dosing follow local protocol and clinical judgment.

Every citation on this page is a real, PubMed-verified reference. The teaching case is an illustrative composite, not a real patient. Medical-education content — not medical advice.