Renal Diseases Overview

Renal Diseases

• A significant loss of renal function in both kidneys, where less than 15% of normal glomerular filtration rate (GFR) remains, defines renal failure.
• A GFR test is a blood test that assesses kidney function.
• Renal failure can be acute (rapidly progressing) or chronic (progressive loss of function over years).
• Acute renal failure is potentially reversible.
• Chronic renal failure can lead to permanent damage.
• Chronic renal failure is a result of progressive kidney damage and function loss.

Stages of Chronic Renal Failure

• Chronic renal failure is categorized into four progressive stages based on decreasing GFR.
• The stages are:
  • Diminished renal reserve
  • Renal insufficiency
  • Renal failure
  • End-stage renal disease

Causes of Chronic Renal Failure

• Diabetes is the most common cause in developed countries.
• Chronic infections
• Prolonged renal obstruction.
• Exposure to toxic chemicals or toxins.
• Drugs (e.g., aminoglycoside antibiotics).
• Hypertension.
• Nephrosclerosis (atherosclerosis of the renal artery).
• Polycystic kidney disease.

Symptoms of Chronic Renal Failure

• Anemia
• Dry skin
• Loss of appetite
• Vomiting
• Bone pain
• Metallic taste in the mouth
• Headaches
• Inability to concentrate urine
• Polyuria/oliguria
• Edema
• GFR decreases from 90 to 30 mL/min
• Increased serum potassium
• Increased blood pressure (BP)
• Weakness and fatigue

Uremic Stomatitis

• Soft tissue changes are caused by urea in saliva, urease enzyme produced by oral microflora and free ammonia which damages oral mucosa.
• Changes include painful plaques and crusts on buccal mucosa, dorsum of tongue, and floor of mouth with gray pseudo membrane exudate and painful ulcers.
• Further complications include bleeding diathesis (petechiae and ecchymosis), irritation and chemical injury of mucosa (ammonium compounds), xerostomia (unpleasant taste), burning mouth, and uriniferous breath odor.
• Other ulcer causes include anemia and viral infections (immunosuppressed).
• Gingival hyperplasia can be caused by cyclosporine and nifedipine (CCB).

Hard Tissue Changes (Uremic Stomatitis)

• Tooth staining is caused by iron supplements.
• Reduced dental caries is caused by urea in saliva.
• Delayed tooth eruption.
• Enamel hypoplasia.
• Oral manifestations of oxalosis include alveolar bone resorption, external root resorption, increased tooth mobility, pain, and an open bite.

Oral Manifestations in Hyperparathyroidism

• Teeth appear more radiopaque against a background of osteoporotic bone.
• Loss of bony trabeculations.
• Ground-glass appearance.
• Total or partial loss of lamina dura.
• Loss of cortical outlines of inferior alveolar sinus.
• Pulpal calcifications.
• Multilocular radiolucency.
• Arterial and oral calcification

Treatment of Chronic Renal Failure

• Careful management of fluids and electrolytes.
• Restriction of dietary protein intake.
• Treatment of anemia
• Renal dialysis.
• Renal transplantation.

Post-streptococcal Glomerulonephritis (PSGN)

• Caused by group A beta-hemolytic streptococci (GAHS) serotype 12, 4, 1 from throat or skin infections.
• Antibodies to streptococcus (anti-streptolysin O) are formed in the circulation.
• Antigen-antibody immune complexes are deposited at the glomerular basement membrane.

Nephritic Syndrome (PSGN)

• Nephritic syndrome is characterized by;
  • Hematuria with acanthocytes
  • RBC casts in the urine.
  • Proteinuria (< 3.5 g/24 h)
  • Hypertension.
  • Oliguria
  • Azotemia
• This syndrome indicates glomerular inflammation.

Clinical Features of Poststreptococcal Glomerulonephritis

• Occurs weeks after group A β-hemolytic streptococcal infections.
• Pharyngitis/tonsillitis is the most common cause (1-2 weeks after infection).
• Skin infections (3-4 weeks after infection).
• Periorbital and peripheral edema.
• Hypertension.
• Tea- or cola-colored urine.
• In Children, typically self-limiting.
• Can lead to rapidly progressive glomerulonephritis (RPGN) → renal insufficiency in adults.

Signs and Symptoms of Glomerulonephritis

• Headache.
• Facial/periorbital edema.
• Lethargic
• Low-grade fever.
• Weight gain.
• Proteinuria.
• Hematuria.
• Oliguria.
• Dysuria

Investigations of PSGN

• Urine analysis.
• Serology (antibody testing).
• Throat swab.
• Renal function tests.

Treatment of Poststreptococcal Glomerulonephritis

• Supportive care, fluid, and sodium restrictions.
• Diuresis within 7-10 days of symptom onset.
• 10 days of systemic antibiotic treatment with penicillin V.

References and Further Readings

• AMBOSS
• Harrison's Principles of Internal Medicine 20th edition (ISBN-13: 978-1259644030)