What is the significance of C3 and C4 (complement component 3 and complement component 4)?

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Last updated: April 17, 2025View editorial policy

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From the Guidelines

C3 and C4 refer to complement components involved in glomerular diseases, with C3 glomerulopathy being a catch-all term that includes C3GN and C3DDD, while also considering C4GN and C4DDD as related diseases. When managing these conditions, it is essential to consider the treatment of C3 glomerulopathy, which encompasses glomerular diseases due primarily to complement dysregulation resulting in discrete deposits of C3 or C4 in the glomerulus 1. The treatment approach should take into account the specific disease entity, such as C3GN, C3DDD, C4GN, or C4DDD, and consider the underlying complement dysregulation. Key points to consider in the treatment of C3 glomerulopathy include:

  • The importance of accurate diagnosis and classification of the disease entity
  • The role of complement dysregulation in the disease pathogenesis
  • The potential use of therapies targeting the complement system, such as eculizumab or ravulizumab, in certain cases 1
  • The need for individualized treatment approaches, taking into account the specific disease characteristics and patient factors. In clinical practice, the treatment of C3 and C4 glomerulopathy should prioritize reducing morbidity, mortality, and improving quality of life, with a focus on managing the underlying complement dysregulation and preventing disease progression 1.

From the Research

C3 C4 Spinal Cord Injuries

  • C3/4 spinal cord injuries are severe and can result in significant disability, with 53.3% of patients showing improvement according to Frankel's classification 2.
  • These injuries can be caused by axial loading mechanisms, and are unique in terms of their infrequency of bony fracture and difficulty in effecting and maintaining reduction 3.
  • Patients with C3/4 spinal cord injuries may require tracheotomy due to severe respiratory disturbance, and have a high mortality rate, with 5 out of 15 patients dying between 2 and 156 months after injury 2.

C3 C4 Disc Herniations

  • C3-C4 disc herniations are uncommon and can present as a painless myelopathy, with symptoms such as hand numbness 4.
  • Early recognition and treatment of C3-C4 disc herniations can lead to favorable outcomes, with improvement in neurological status 4.
  • C3-C4 disc herniations may be underdiagnosed, but have a more favorable outcome when diagnosed and treated promptly 4.

Treatment Options

  • Epidural steroid injections have been shown to be effective in treating symptomatic lumbar herniated discs, with 77% of patients experiencing successful resolution or significant decrease of their symptoms 5.
  • Physical therapy and epidural steroid injections have been shown to be effective in treating lumbar spinal stenosis, with significant improvements in pain and functional parameters 6.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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