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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Nephrology

Symptoms & Red Flags: When to Seek Urgent Care

At a Glance

C1q nephropathy may be silent or cause blood and protein in the urine, foamy urine, high blood pressure, or swelling. Sudden breathing trouble, chest pain, one-sided limb swelling, very low urine output, severe infection symptoms, or severe high blood pressure need urgent evaluation.

C1q nephropathy (C1qN) affects every patient differently. For some, it is a “silent” finding discovered during a routine checkup. For others, it causes significant symptoms that require close monitoring and medical intervention. Understanding what is typical and what is an emergency is essential for managing this condition safely.

Range of Symptoms

The symptoms of C1qN generally fall into three categories based on how the kidneys are behaving:

  • Asymptomatic: You may feel perfectly fine, but a urine test shows small amounts of blood (hematuria) or protein (proteinuria) [1][2].
  • Moderate Symptoms: You might notice “foamy” or “bubbly” urine (a sign of protein) or mild high blood pressure (hypertension) [3][4].
  • Nephrotic Syndrome: This is a more severe presentation where the kidneys leak large amounts of protein. It is defined by three main features: heavy proteinuria, low levels of the protein albumin in the blood, and visible swelling (edema) [5][6].

Understanding Edema (Swelling)

Swelling is the most common visible symptom of C1qN-related nephrotic syndrome.

  • What is normal: It often follows a pattern—puffiness around the eyes in the morning that may shift to the ankles or legs by the evening [7]. This mild, daily fluctuation should be reported to your nephrology team, but it is not typically an immediate emergency on its own [8].
  • What to watch for: If swelling progresses to the abdomen (ascites) or makes your clothes and shoes suddenly not fit, it indicates that the kidneys are struggling to manage fluid balance and requires prompt medical attention [9][10].

Important Warning: Never adjust your fluid intake or diuretic (water pill) doses on your own based on how your swelling looks. Trying to correct fluid balance without medical guidance can lead to severe dehydration or acute kidney injury [11][12].

When to Seek Urgent Medical Care

While many symptoms can be managed during scheduled office visits or through a call to the clinic, certain “red flags” require immediate medical evaluation—either a same-day call to your specialist or a trip to the emergency room.

1. Blood Clots (Thrombosis)

Nephrotic syndrome changes the balance of clotting factors in your blood, making you much more likely to develop dangerous clots [13][14]. Call 911 or go to the emergency room immediately for:

  • Pulmonary Embolism: Sudden shortness of breath, chest pain (especially when breathing deeply), or coughing up blood [15][16].
  • Deep Vein Thrombosis (DVT): Sudden, painful swelling in one leg or arm that may feel warm or look red [13][17].
  • Renal Vein Thrombosis: Sudden, severe pain in the side (flank), back, or abdomen, sometimes accompanied by bloody urine [18][17].

2. Severe Infection

The loss of protective proteins in the urine and the use of immunosuppressant medications (like steroids) make it harder for your body to fight infections [19]. Immunosuppressants can also blunt a fever, meaning a serious infection might not cause a very high temperature. Seek emergency care for:

  • A fever that meets the specific threshold set by your doctor’s individualized action plan (this threshold varies greatly by age and medication) [20].
  • Severe abdominal pain, tenderness, or vomiting, which can signal a serious infection called peritonitis [21][22].
  • A “toxic” appearance—feeling extremely ill, lethargic, or confused [22].

3. Acute Kidney Injury (AKI) and Dehydration

Sometimes, the fluid in your body stays in the tissues (causing swelling) but leaves your bloodstream dangerously “dry” or dehydrated (hypovolemia) [11]. Seek emergency care for:

  • A marked decrease in urine output or not urinating at all (follow your doctor’s specific guidelines for your age and baseline) [23].
  • Dizziness, fainting, or a rapid, pounding heart rate [12].
  • New or worsening confusion or extreme fatigue [24].

4. Severe High Blood Pressure

  • Extremely high blood pressure readings accompanied by a severe headache, visual changes, or chest pain require immediate emergency evaluation.

If you are ever unsure whether a symptom is an emergency, use your individualized written action plan and call your nephrology team’s after-hours line for guidance.

Common questions in this guide

What symptoms can C1q nephropathy cause?
C1q nephropathy can cause no noticeable symptoms, with blood or protein found on a urine test. Other people develop foamy urine, high blood pressure, or nephrotic syndrome, which involves heavy protein loss, low blood albumin, and swelling.
What does swelling mean, and when is it urgent?
Morning puffiness around the eyes or ankle swelling later in the day can occur with C1q nephropathy and should be reported to the kidney team. Swelling that spreads to the abdomen, rapidly makes clothes or shoes tight, causes pain, or makes breathing difficult needs prompt medical attention; breathing difficulty is an emergency.
Could C1q nephropathy increase my risk of a blood clot?
Nephrotic syndrome can make blood clots more likely because the balance of clotting factors changes when large amounts of protein are lost. Call emergency services for sudden shortness of breath, chest pain, coughing up blood, or painful swelling in one arm or leg; sudden severe flank, back, or abdominal pain with bloody urine also needs immediate evaluation.
What are the infection warning signs if I take immunosuppressants?
Loss of protective proteins in the urine and immunosuppressant medicines can make infections harder to fight, and these medicines may keep a fever from becoming very high. Follow the fever threshold in your personal action plan and seek emergency care for severe abdominal pain with vomiting, extreme lethargy or confusion, or feeling extremely ill.
How can I tell if low urine output is an emergency?
A marked decrease in urine, no urination, dizziness, fainting, a rapid pounding heartbeat, new confusion, or extreme fatigue can signal dehydration or acute kidney injury. Seek emergency medical care and do not change your fluid intake or water-pill dose unless your clinician gives you specific instructions.
When is high blood pressure with C1q nephropathy an emergency?
An extremely high blood pressure reading needs immediate emergency evaluation when it occurs with a severe headache, vision changes, or chest pain. If you are unsure how to respond to a reading or symptom, use your written action plan and call your nephrology team's after-hours line.

Get notified when new evidence is published on C1q nephropathy.

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References

References (24)
  1. 1

    C1q Nephropathy: The Unique Underrecognized Pathological Entity.

    Devasahayam J, Erode-Singaravelu G, Bhat Z, et al.

    Analytical cellular pathology (Amsterdam) 2015; (2015()):490413 doi:10.1155/2015/490413.

    PMID: 26640759
  2. 2

    Predominant but silent C1q deposits in mesangium on transplanted kidneys - long-term observational study.

    Kanai T, Akioka Y, Miura K, et al.

    BMC nephrology 2018; (19(1)):82 doi:10.1186/s12882-018-0874-9.

    PMID: 29625558
  3. 3

    A clinicopathological and prognostic study of 18 children with C1q nephropathy and focal segmental glomerulosclerosis: an 18-year experience from a single center.

    Peng Y, Ju T, Gao C, et al.

    Journal of nephrology 2023; (36(6)):1615-1625 doi:10.1007/s40620-023-01679-9.

    PMID: 37428438
  4. 4

    C1q Nephropathy in Children with Nephrotic Syndrome: Treatment Strategies and Outcomes.

    Gaur S, Patrick R, Vankalakunti M, Phadke K

    Indian journal of nephrology 2022; (32(1)):54-59 doi:10.4103/ijn.IJN_578_20.

    PMID: 35283565
  5. 5

    Endocrine Disorders in Nephrotic Syndrome-A Comprehensive Review.

    Mizdrak M, Smajic B, Mizdrak I, et al.

    Biomedicines 2024; (12(8)) doi:10.3390/biomedicines12081860.

    PMID: 39200324
  6. 6

    Nephrotic syndrome in infants and children: pathophysiology and management.

    Downie ML, Gallibois C, Parekh RS, Noone DG

    Paediatrics and international child health 2017; (37(4)):248-258 doi:10.1080/20469047.2017.1374003.

    PMID: 28914167
  7. 7

    Diagnosis and management of nephrotic syndrome.

    McCloskey O, Maxwell AP

    The Practitioner 2017; (261(1801)):11-5.

    PMID: 29020719
  8. 8

    [Idiopathic nephrotic syndrome (INS) in children in Dakar: about 40 cases].

    Keita Y, Lemrabott AT, Sylla A, et al.

    The Pan African medical journal 2017; (26()):161 doi:10.11604/pamj.2017.26.161.10130.

    PMID: 28533882
  9. 9

    Mechanisms and management of edema in pediatric nephrotic syndrome.

    Kallash M, Mahan JD

    Pediatric nephrology (Berlin, Germany) 2021; (36(7)):1719-1730 doi:10.1007/s00467-020-04779-x.

    PMID: 33216218
  10. 10

    Nephrotic Syndrome Without Nephrotic Range Proteinuria.

    Sheikh JA, Syed U, Osama SM

    Cureus 2024; (16(7)):e64342 doi:10.7759/cureus.64342.

    PMID: 39131015
  11. 11

    Pathophysiology, Evaluation, and Management of Edema in Childhood Nephrotic Syndrome.

    Ellis D

    Frontiers in pediatrics 2015; (3()):111 doi:10.3389/fped.2015.00111.

    PMID: 26793696
  12. 12

    Urinary potassium to urinary potassium plus sodium ratio can accurately identify hypovolemia in nephrotic syndrome: a provisional study.

    Keenswijk W, Ilias MI, Raes A, et al.

    European journal of pediatrics 2018; (177(1)):79-84 doi:10.1007/s00431-017-3029-2.

    PMID: 29022080
  13. 13

    Risk of Arterial Thromboembolism, Venous Thromboembolism, and Bleeding in Patients with Nephrotic Syndrome: A Population-Based Cohort Study.

    Vestergaard SV, Birn H, Darvalics B, et al.

    The American journal of medicine 2022; (135(5)):615-625.e9 doi:10.1016/j.amjmed.2021.11.018.

    PMID: 34979093
  14. 14

    Thromboembolism in nephrotic syndrome: controversies and uncertainties.

    Parker K, Ragy O, Hamilton P, et al.

    Research and practice in thrombosis and haemostasis 2023; (7(6)):102162 doi:10.1016/j.rpth.2023.102162.

    PMID: 37680313
  15. 15

    Unprovoked Pulmonary Embolism with Bilateral Deep Vein Thrombosis Revealing Occult Nephrotic Syndrome Due to Seronegative Membranous Nephropathy.

    Eser S, Serra A, Kleber M, Brombacher F

    European journal of case reports in internal medicine 2026; (13(4)):006359 doi:10.12890/2026_006359.

    PMID: 41988553
  16. 16

    Acute myocardial infarction in a child with nephrotic syndrome.

    Charfeddine S, Yousfi C, Maalej B, et al.

    Revista portuguesa de cardiologia 2021; (40(6)):457.e1-457.e4 doi:10.1016/j.repce.2021.07.011.

    PMID: 34274088
  17. 17

    Isolated superior mesenteric vein thrombosis in an adult with nephrotic syndrome due to minimal change disease: a case report.

    Dakak AG, Mahgoub MK, Jalkhi TA, et al.

    Journal of medical case reports 2025; (19(1)):149 doi:10.1186/s13256-025-05130-4.

    PMID: 40170178
  18. 18

    Rapid renal salvage in acute renal vein thrombosis secondary to membranous nephropathy using large-bore mechanical thrombectomy.

    Singh SD, Gan CC, Lee L, et al.

    Thrombosis journal 2026; (24(1)).

    PMID: 41896885
  19. 19

    Nephrotic syndrome: pathophysiology and consequences.

    Ponticelli C, Moroni G

    Journal of nephrology 2023; (36(8)):2179-2190 doi:10.1007/s40620-023-01697-7.

    PMID: 37466816
  20. 20

    Infections in Children With Nephrotic Syndrome: Twenty Years of Experience.

    Lebel A, Kropach N, Ashkenazi-Hoffnung L, et al.

    Clinical pediatrics 2020; (59(7)):692-698 doi:10.1177/0009922820908583.

    PMID: 32116004
  21. 21

    Managing concurrent nephrotic syndrome, spontaneous bacterial peritonitis, and herpes zoster in an immunocompromised child: Diagnostic difficulties and treatment outcomes.

    Adrizain R, Modjaningrat I, Winyarti , et al.

    IDCases 2026; (43()):e02489 doi:10.1016/j.idcr.2026.e02489.

    PMID: 41551359
  22. 22

    Fulminant campylobacter jejuni bacteremia complicating steroid-dependent nephrotic syndrome in a pediatric patient: a case report.

    Elmezayen ZW, Adi M, Albaroudi FH, Elmezayen RW

    BMC infectious diseases 2026; (26(1)).

    PMID: 41947061
  23. 23

    Acute kidney injury complicating nephrotic syndrome of minimal change disease.

    Meyrier A, Niaudet P

    Kidney international 2018; (94(5)):861-869 doi:10.1016/j.kint.2018.04.024.

    PMID: 29980292
  24. 24

    AKI in Children Hospitalized with Nephrotic Syndrome.

    Rheault MN, Zhang L, Selewski DT, et al.

    Clinical journal of the American Society of Nephrology : CJASN 2015; (10(12)):2110-8 doi:10.2215/CJN.06620615.

    PMID: 26450933

This page describes C1q nephropathy symptoms and emergency warning signs for informational purposes only; it does not constitute medical advice. Follow your individualized plan and contact your nephrology team or emergency services for urgent concerns.

Guide contents C1q nephropathy
Research & Literature
02 Pathology & Diagnosis 04 Standard of Care