C1q Nephropathy is a kidney dysfunction caused by kidney C1q protein deposits in kidney tissue. C1q is a normal protein, which is found in normal healthy individual. In this article, we will discuss in detail the clinical presentation, diagnosis, causes, and treatment for C1q nephropathy.
How Is C1q Nephropathy Defined?
- C1q protein is a normal protein that circulates in blood. Protein molecule C1q is deposited in the kidney resulting in activation of immune system.1
- Immune system activation within kidney causes inflammatory changes in renal (kidney) tissue.
- Disease is often observed in children as a milder disease.
- The renal (kidney) inflammatory changes cause excretion of excessive amount of protein in urine (proteinuria). The disease progresses to nephrotic syndrome.
- The C1q protein deposits are observed under microscope following special stain of biopsy samples of kidney.
- C1q Nephropathy has been recognized recently following advanced technique of stain used to immune proteins in kidney.
Causes Of C1q Nephropathy
- Nephropathy is caused by inflammatory disease of glomerulus caused by C1q protein deposits.2
- Immune protein C1q when deposited in kidney tissue causes inflammation of the glomerulus.2
- The reason why C1q immune protein deposits in few patients is not known.
- Autoimmune Disease– Crescent glomerulonephritis is observed in patients suffering with autoimmune disease. Few case report has suggested renal deficiency in patient suffering with lupus is caused by C1q protein, which was found in blood and kidney biopsy study.3
Symptoms Of C1q Nephropathy
- C1q Deposits Nephropathy- Protein deposits causes advanced kidney disease known as nephrotic syndrome.3
- Fluid Retention-
- Edema Lower Leg- The most common symptom of C1q Nephropathy is profound edema or swelling, usually beginning in the lower extremities and spreading into the hips and abdomen.
- Pitting Edema of the Feet- Fluid retention causes bilateral pitting edema of the feet. Swelling may extend in entire lower leg.
- Pleural Effusion- Water may collect in pleural space resulting in pleural effusion. Pleural effusion causes difficulties of breathing or dyspnea.
- Hepatomegaly- Fluid retention of water may cause enlarged liver (hepatomegaly).
- High Blood Pressure2–
- Hypertension or high blood pressure is caused by retention of fluid and excessive secretion of angiotensin enzyme.
- Headache– headache may be the symptom caused by high blood pressure.
- Irregular Heart Beats (Arrhythmia)-
- Hyperkalemia– Blood level of Potassium is often high in kidney dysfunction. Higher potassium level in blood causes irregular heartbeats.
- High Cholesterol
- Blood cholesterol level is high.
- Hyper-Coagulation Of The Blood
- Blood is often hyper coagulated, which results in forming premature blood clots.
Diagnosis of C1q Nephropathy
- Proteinuria- Urine protein levels are high. Urine collected for 24 hours and urine protein loss is calculated.
- Hematuria- RBCs observed in urine
- Low Urine Output- Urine output measured.
- BUN level- Blood urea nitrogen level is high
- Creatinine level-Creatinine level is high
- Cholesterol level- High Cholesterol level
- C1q Deposition- Immune protein level is so minute that it can only be observed with microscope.
- Diagnostic Procedure- Renal biopsy is the only definitive diagnostic test available to confirm diagnosis of C1q nephropathy.
- CT scan images of the kidney studied to evaluate the kidney tissue damaged
Magnetic Resonance Imaging (MRI)-
- MRI images provide three-dimensional view of the kidney. MRI is an alternative study to CAT scan.
Treatment For C1q Nephropathy
- 24 hours urine output is calculated and measured so equal volume of daily fluid is replaced.
- Oral fluid intake is documented.
- Dietitian is consulted to balance fluid intake.
- Hyperkalemia treated with following medication
- Blood electrolyte monitor to correct bicarbonate, chlorine and sodium level.
- Ace Inhibitors
- High blood pressure is treated with ace inhibitors
- Ace inhibitors also protect kidney
- Beta Blocker- Beta blocker is used if hypertension is associated with irregular heartbeats.
Treatment of Hyperkalemia-
- Intravenous Calcium- Calcium is injected intravenously after mixing with normal saline. Calcium injection is given while monitoring patient’s heart and oxygenation.
- Intravenous Insulin Therapy- Intravenous insulin is injected with intravenous glucose and sodium bicarbonate to drive the potassium in the cell from extracellular fluid and blood.
- Cation Exchange Resins- Treatment exchanges potassium and excretes. Simultaneously blood electrolyte is monitored to check the level of other electrolytes.
Albumen and globulin blood level are monitored. The protein deficiency is replaced with Intravenous protein injection or special oral protein diet.
- Corticosteroid is used in high dosage to suppress immune response initiated by C1q protein within kidney tissue.
- Cyclosporine is also used if infection is suspected to control infection and immune response by kidney.
Lipid (cholesterol) Lowering Agents-
- Bile acid resins
End Stage Renal Disease not responding to conservative and established medical treatment.
1. Diverse clinical and histology presentation in c1q nephropathy.
Malleshappa P1, Vankalakunti M.
Nephrourol Mon. 2013 Jul 1;5(3):787-91.
2. Association of C1q deposition with renal outcomes in IgA nephropathy.
Lee HJ1, Choi SY, Jeong KH, Sung JY, Moon SK, Moon JY, Lee SH, Lee TW, Ihm CG.
Clin Nephrol. 2013 Aug;80(2):98-104. doi: 10.5414/CN107854.
3. Serum levels and renal deposition of C1q complement component and its antibodies reflect disease activity of lupus nephritis.
Tan Y1, Song D, Wu LH, Yu F, Zhao MH.
BMC Nephrol. 2013 Mar 19;14:63. doi: 10.1186/1471-2369-14-63.
4. C1q nephropathy in children: clinical characteristics and outcome.
Gunasekara VN1, Sebire NJ, Tullus K.
Pediatr Nephrol. 2014 Mar;29(3):407-13.