Evidence map›Paper›PMID 41917895›Full record

ArticleBMC nephrology2026

Urine microscopy revealing a metabolic disorder: a case report.

Diana Santos, Miguel Brito Lança, David Navarro, Pedro Baltazar, Cristina Jorge, Luís Campos Pinheiro, Nuno Moreira Fonseca

Abstract readCase Reports
In one paragraph

Article in BMC nephrology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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2 · The registry

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

7 authors.

Diana SantosNephrology Department, Unidade Local de Saúde São José, Lisbon, Portugal.ORCID 0009-0003-4006-4586
Miguel Brito LançaCentro Clínico Académico de Lisboa, Lisbon, Portugal.ORCID 0000-0002-9801-849X
David NavarroNephrology Department, Unidade Local de Saúde São José, Lisbon, Portugal.ORCID 0000-0002-1977-794X
Pedro BaltazarCentro Clínico Académico de Lisboa, Lisbon, Portugal.ORCID 0000-0002-8197-2965
Cristina JorgeNephrology Department, Unidade Local de Saúde São José, Lisbon, Portugal.ORCID 0000-0001-7850-4805
Luís Campos PinheiroCentro Clínico Académico de Lisboa, Lisbon, Portugal.
Nuno Moreira FonsecaNephrology Department, Unidade Local de Saúde São José, Lisbon, Portugal. nuno.mf@nyu.edu.ORCID 0000-0003-0821-2764

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundPrimary hyperoxaluria type 3 is a rare autosomal recessive disorder caused by HOGA1 mutations, leading to recurrent calcium oxalate nephrolithiasis. Diagnosis is often delayed, and 24-hour urine oxalate measurements can be unreliable in patients with normal kidney function. Urine microscopy can detect high-density calcium oxalate monohydrate crystals, providing a rapid diagnostic clue. CASE PRESENTATION: A 31-year-old woman with recurrent nephrolithiasis since age 9 had undergone prior percutaneous nephrolithotomy and ureteroscopy. Urine microscopy revealed abundant calcium oxalate monohydrate crystals (280/mm³), and stone analysis showed mixed calcium phosphate, calcium oxalate dihydrate and monohydrate. Genetic testing confirmed homozygous HOGA1 mutation (c.700 + 5G > T). Conservative management with hydration, dietary calcium, and potassium citrate normalized citrate but not crystalluria. Adjunctive phytate therapy led to disappearance of calcium oxalate monohydrate crystals within weeks. Renal function and residual stones remained stable over 24 months.

conclusionDetection of > 200 calcium oxalate monohydratecrystals/mm³ is highly suggestive of primary oxaluria type 3. Urine microscopy is rapid, inexpensive, and complements genetic testing. Conservative therapy remains central, and adjunctive measures like phytate may help reduce crystallization risk.

Indexed as

Calcium OxalateHyperoxaluria, PrimaryAdultCrystalluriaFemaleHumansMicroscopyOxo-Acid-LyasesUrinary Sediment Analysis4-hydroxy-2-oxoglutarate aldolaseCalcium OxalateOxo-Acid-LyasesCase reportCrystalluriaNephrolithiasisPrimary hyperoxaluriaUrine microscopy

Identifiers

PMID41917895
PMCPMC13162489

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