Chronic Renal Diseases: Pathological aspects Dr Rodney Itaki Division of Pathology, SMHS, UPNG Anatomical Pathology Discipline.

Gross anatomy Ref: Goggle Images

Microanatomy Robins Pathological Basis of Diseases, 6th Ed. Figure 21.1

Glomeruli - Ultra filtration

Glomeruli & Renal Capsule

Blood Supply

Juxtaglomerular Apparatus +low BP & Ischaemia +Low NaCl

Renin-Angiotensin-Aldosterone System Ref: www.commons.wiki.org

Chronic Renal Disease Definition: Chronic renal disease (CRD) is a pathophysiologic process with multiple etiologies, resulting in the inexorable attrition of nephron number and function, and frequently leading to end-stage renal disease (ESRD). Irreversible deterioration in renal function (C.R.W.Edwards et al, 1998, pg.631) Ref: Harrison 15th Ed.

Azotemia There is azotemia in chronic renal failure. Azotemia is the biochemical state in which there is an elevation of: Blood urea nitrogen (BUN) and Creatinine levels when there is a decreased glomerular filtration rate (GFR). Persistent azotemia gives rise to signs, symptoms and biochemical abnormalities, which is referred to as uremia.

Types of azotemia Type Feature Pre-renal azotemia Due to hypoperfusion of kidneys. For e.g. in congestive heart failure, shock, hemorrhage, and dehydration. Post-renal azotemia Due to any obstruction to the urinary flow below the level of kidneys. [Note azotemia is not specific for chronic renal failure.]

Uremia Definition: Uremia is the clinical and laboratory syndrome, reflecting dysfunction of all organ systems as a result of untreated or under-treated acute or chronic renal failure. (CD-ROM 15th Harrison)

Pathogenesis Due to disturbances in water, electrolytes & acid-base balance. Accumulation of substances such as phosphate, parathyroid hormone, urea, creatinine, guanidine, phenols,& idoles.

Fig: Pathophysiologic pathway of chronic renal failure. ©2003 American Medical Association. All rights reserved. on July 17, 2008 www.archinternmed.com Downloaded from

Figure 1. Sympathetic over-activity and disease progression in chronic renal failure

Pathophsiology of Chronic Renal Failure Diminished renal reserve 2. Renal insufficiency 3. Renal failure 4. End-stage renal disease (Chronic Renal Failure)

End Stage Renal Disease (ESRD) In ESRD there is a degree of irreversible damage to the kidney and its function. The patient usually becomes dependent on renal replacement therapy (dialysis or transplantation) in order to avoid life-threatening uremia.

Gross Morphology

Microscopic Morphology Tubular atrophy Interstitial fibrosis Enlarged & hypertrophic tubules Thickened basement membrane

Clinical Features of Uraemia Anaemia Metabolic bone diseases(renal osteodystrophy) Neuropathy Myopathy Endocrine abnormalities Hypertension & atherosclerosis Acidosis Susceptibility to infection

Signs & Symptoms of Uraemia Vague-ill health Generalized weakness & lack of energy Breathlessness on exertion Anorexia Nausea & vomiting particularly in mornings Disordered intestinal motility Headaches Visual disturbances Pruritis Pallor Pigmentations Loss of libido

Laboratory Investigation Aim - Diagnosis and disease monitoring FBC - anaemia UEC – electrolyte imbalances, urea and nitrogen abnormalities Renal biopsy Others – Ca, phosphate, EPO, etc. Genetic & immunological studies - transplant

Chronic Renal Diseases - Causes The causes of chronic renal failure can be due to any disease process affecting the following structures: Glomeruli (glomerulonephritis) Tubules (reflex nephropathy) Interstitium (pyelonephritis, reflux nephropathy) Blood vessels (Hypertension)

Glomerular Diseases Types: Immune or Non-immune mediated injury

Immune mediated Glomerular Diseases Immune mechanism can be of antibody-associated injury. Two forms are known: Immune response resulting in injury due to deposition of soluble circulating antigen-antibody complexes in the glomeruli. Referred to as Circulating Immune complex injury. Immune response resulting injury due to antibodies reacting in situ within the glomerulus. Referred to as Cell Mediated Injury. Others may be due to cytotoxic antibodies directed against the glomerular cells.

Non-immune Mediated Glomerular Diseases 1. Metabolic glomerular injury. Diabetic nephropathy: the glomerular lesion is glomerulosclerosis whereby there is thickening of the glomeular basement membrane. 2. Hemodynamic glomerular injury. This is due to the high intra-glomerular pressure caused by systemic hypertension or local change in glomerular hemodynamics (glomerular hypertension). 3. Toxic glomerulopathies. The toxic verotoxic from the E.Coli is directly toxic to renal endothelium and induces hemolytic-uremic syndrome in patients with infective diarrhea caused by E.Coli.Verotoxic interacts with specific cell membrane receptor inducing thrombotic microangiopathy.

Non-immune Mediated Glomerular Diseases 4. Deposition disease. There is deposition of abnormal proteins in the glomeruli inducing inflammatory reaction or glomerulosclerosis. For e.g. amyloidosis, cryoglobulins, light and heavy chain deposition disease. 5. Infectious glomerulopathies. Infectious microorganisms can cause injury by: Direct infection of renal cell Elaboration of nephrotoxic e.g. E.Coli Intraglomerular deposition of immune complexes e.g. post-infectious glomerulonephritis. Providing chronic stimulus for amyloidosis. 6. Inherited glomerular diseases. A common e.g. is: Alport’s disease: Transmitted, as X-linked dominant trait. There is mutation in COL4A5 gene that encodes -5 chain of type IV collagen located on X-chromosome. The glomerular basement membrane (GBM) is affected.

The determinants of the severity of glomerular damage are The nature of primary insult and secondary mediator system that evoke it. The site of injury within the glomerulus. The speed of onset, extend and intensity of disease.

Common Chronic Renal Failure Causes Non-Immune Mediated - Diabetic Nephropathy Immune Mediated – Glomerulonephritis Blood vessel - Hypertension Interstitial injury & Tubules - Reflux nephropathy in children Interstitial, tubules & Glomerular - Polycystic kidney disease Interstitial & tubules - Kidney infections & obstructions Source: Wendy DeMartino, MD, Teaching Slides. Downloaded via Goggle Search.

Diabetic Nephropathy Ref: Robins Pathological Basis of Diseases, 6th E. Table 20.1

Diabetic Nephropathy Capillary BM thickening. Diffuse glomerulosclerosis. Nodular glomerulosclerosis. Ref: www.unckidneycentre.org

Basement membrane Thickening Thickened BM Ref: www.intechopen.com

Amyloidosis Amyloid deposits Deposition of abnormal protein in the glomerulus & blood vessel wall Amyloid deposits

Amyloidosis Congo red stain. Examined under polarization microscopy. “Apple-green” birefringence. Ref: www.pathology.vcu.edu

Glomerulonephritis Ref: Robins Pathological Basis of Diseases, 6th Ed. Table 21.3

Glomerulonephritis Ref. Robins Pathological Basis of Diseases, 6th Ed. Figure 21.29

Histological Types of GN Post-streptococcal GN Rapidly Progressive Glomerulonephritis Membranous GN Focal glomerulosclerosis Membranoproliferative GN

Post-streptococcal GN Normal glomerulus Acute proliferate GN Hypercellularity due to intercapillary leucocytes & proliferation of glomerular cells Ref: Robins Pathological Basis of Diseases, 6th Ed. Fig 21.16

Rapidly Progressive (Crescentic) GN Ref: www.geekymedics.com

Crescent GN Collapsed glomerular tufts Mass of crescent shaped proliferating cells & leucocytes Ref: Robins Pathological Basis of Diseases, 6th Ed. Fig 21.17

Membranous GN Diffuse thickening of capillary wall without increase in number of cells Diagrammatic representation Ref: Robins Pathological basis of Diseases, 6th Ed. Fig. 21.19

Minimal Change Disease (Lipoid Nephrosis) Visceral epithelial cells show uniform and diffuse effacement of foot process Thin BN. No proliferation

Minimal Change Disease Normal glomerular tuft. No hypercellularity. Thin BM. Ref: www.kidneypathology.com

Focal Glomerular Sclerosis Sclerotic segment shows deposition of hyaline masses Lipid in sclerotic area (small vacuoles) Foam cells Ref:www.med.niigata-u.ac.jp

Membranoproliferative GN Differentiation based on electron microscopy Ref: Robins Pathological Basis of Diseases, 6th Ed. Fig 21.24

Membranoproliferative GN Thickened in BM Proliferation of mesangial cells (glomerular cells) Leukocyte infiltration Ref: Robins Pathological Basis of Diseases, 6th Ed. Fig 21.23

IgA Nephropathy (Berger Disease) IgA deposited within mesangium increasing its cellularity Immunofluorescence demonstrating positivity with antibody to IgA. Ref: www.pathologyoutlines.com

Focal Proliferative & Necrotising GN (Focal GN) Main differential diagnosis for Focal glomerulosclerosis as histological features very similar. Main lesions are predominantly proliferative. Focal necrosis & fibrin deposition often occur within lesions. Occur as part of a systemic disease (e.g. SLE), component of known glomerular disease (e.g. IgA nephropathy) or primary (cause unknown).

Blood Vessel Injury - Hypertension Atherosclerosis: Multifactorial The vascular injury is due to cholesterol- containing micro-emboli (atheroemboli) dislodged from atheromatous plaque in larger arteries. The micro-emboli occlude the small vessels in the kidney. Direct injury to blood vessel wall. It may result in renal artery stenosis and ischemic renal diseases.

Pathogenesis Of Disease Involving Blood Vessels Hypertension: The persistent exposure of renal circulation to intraluminal hypertension results in hyaline arteriosclerosis of the afferent arterioles and finally loss of function (nephrosclerosis). That is, Benign arteriolar nephrosclerosis: found in patients who are hypertensive for sometime with BP > 150/90 mmHg. Hypertension has not progressed to malignant form. Malignant arteriolar nephrosclerosis: found in patients who have long-standing benign hypertension and not known hypertensive. There is sudden elevation in BP (diastolic  130mmHg). There is accompanied papilledema, cardiac decompensation, CNS involvement, and progressive renal deterioration.

Hypertension – Renal Changes Hyperplastic arteriolitis (onion-skin lesion) Fibrinoid necrosis of afferent arteriole. Robins Pathological Basis of Diseases, 6th Ed. Figure 21.20

Others Reflux nephropathy – renal scaring and loss of glomeruli. Polycystic kidney diseases – multiple dilated cysts. Genetic. Kidney infections & obstructions – acute to chronic inflammation. Renal scaring and loss of glomeruli. Focal GN/Focal proliferative & nectrotising GN. Main differential diagnosis of Focal sclerosis GN.

Complications Endocrine abnormalities Muscle dysfunction Anemia Bone disease Skin disease Gastrointestinal complications Metabolic abnormalities Endocrine abnormalities Muscle dysfunction Nervous complications Cardiovascular

Prognosis Poor Treatment can only slow progression Renal transplant offers true cure (but has its own complications).

END Main reference: Robins Pathological Basis of Diseases, 6th Ed. Chapter on Kidney & Endocrine diseases.