Kidney Functions and Renal Disease Classification

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the main consequence of decreased glomerular filtration rate (GFR) in relation to azotæmia?

Reduced water absorption

Elevated glomerular permeability to proteins

Reduced secretion of hormones from the kidney

Increased blood urea nitrogen and creatinine levels (correct)

Which of the following is NOT a characteristic feature of nephrotic syndrome?

Severe œdema

Heavy proteinuria over 3.5 g/day

Hypoalbuminæmia

Hypertension (correct)

What type of renal disease is most commonly associated with immunological mediation?

Interstitium disease

Tubular disease

Glomerular disease (correct)

Vascular disease

In what condition is the presence of bacteriuria and pyuria most commonly observed?

Urinary tract infection (UTI) Signup and view all the answers

Which of the following correctly describes the composition of the glomerular capillary wall?

Includes mesangial cells for support Signup and view all the answers

What characterizes acute renal failure?

Presence of oliguria or anuria along with azotæmia Signup and view all the answers

Which of the following accurately describes the permeability characteristics of the glomerulus?

Allows significant passage of small solutes but not proteins Signup and view all the answers

Which major renal syndrome typically presents with asymptomatic haematuria or proteinuria?

Asymptomatic glomerular disease Signup and view all the answers

What is a key characteristic of Type I crescentic glomerulonephritis?

Presence of anti-GBM antibodies with linear deposits of IgG and C3 Signup and view all the answers

Which of the following conditions is NOT usually associated with Type II crescentic glomerulonephritis?

Hypercalcemia Signup and view all the answers

What is a distinctive histological feature of Acute Tubular Necrosis (ATN)?

Necrosis of short segments of renal tubules, particularly at the PCT Signup and view all the answers

Which type of hypersensitivity reaction involves the deposition of immune complexes that are not of glomerular origin?

Type III hypersensitivity reaction Signup and view all the answers

Which factor contributes to the increased risk of Acute Pyelonephritis?

Urinary tract instrumentation Signup and view all the answers

What is the histological hallmark of Classic Chronic Pyelonephritis?

Scarring and deformity of the pelvicalyceal system Signup and view all the answers

In minimal change disease, what microscopic feature is observed in the visceral epithelial cells?

Loss of foot processes Signup and view all the answers

Which type of renal cell carcinoma is most common in adults?

Clear cell carcinoma Signup and view all the answers

Which of the following diseases is commonly associated with membranous glomerulonephritis?

SLE Signup and view all the answers

What typically does NOT characterize IgA Nephropathy?

Rapidly progressive decline in renal function Signup and view all the answers

What is the primary characteristic of focal segmental glomerulosclerosis?

Sclerosis affecting some glomeruli Signup and view all the answers

What is the most common tumor type found in the urinary bladder?

Transitional cell carcinoma Signup and view all the answers

What type of immune response primarily underlies the conditions classified as nephritic syndromes?

Cell-mediated immunity Signup and view all the answers

Which of these statements about renal tumors is incorrect?

Wilms' tumor is primarily a condition in adults Signup and view all the answers

What is a known direct cause of nephrotic syndrome in adults?

Chronic hepatitis B Signup and view all the answers

Which renal condition is associated with vesicoureteric reflux?

Acute Pyelonephritis Signup and view all the answers

Which microscopic finding is NOT typical of rapidly progressive (crescentic) glomerulonephritis?

Thickening of GBM Signup and view all the answers

Which pattern of injury is characterized by the presence of antibodies reacting with antigens located on visceral epithelial cells?

Immune complex in situ Signup and view all the answers

What typifies the prognosis of membranoproliferative glomerulonephritis?

Uniformly poor prognosis Signup and view all the answers

What is the most frequent cause of nephrotic syndrome in children?

Minimal change disease Signup and view all the answers

In which condition do antibodies target the glomerular basement membrane and lead to crescentic glomerulonephritis?

Goodpasture’s syndrome Signup and view all the answers

What type of immune response is primarily responsible for the resolution of post-streptococcal glomerulonephritis?

Humoral immunity Signup and view all the answers

What is one of the common features of nephritic syndromes?

Hematuria Signup and view all the answers

Study Notes

Diseases of The Urinary System:

Functions of the kidney:

1. 2. 3. Excretion of waste products of metabolism.

Regulation of body water and salt.

Maintenance of acid base balance.

4. Secretion of various hormones.

Diseases of the kidney are facilitated by classifying them into diseases of glomeruli,

tubules, interstitium and blood vessels. Diseases of the glomeruli are often immunologically

mediated, while diseases of tubules and interstitium are often due to toxic or infectious agents.

Clinical Manifestations of Renal Diseases:

Azotæmia; is a biochemical abnormality that refers to an elevation of blood urea nitrogen

(BUN) and Creatinine levels and is largely related to a decreased glomerular filtration rate (GFR).

It could be caused by prerenal, renal and postrenal disorders. Uræmia refers to a constellation of

symptoms associated with elevated BUN.

Major Renal Syndromes:

1. Acute nephritic syndrome: is characterized by the acute onset of grossly visible

hæmaturia, proteinuria, and hypertension. It is the classic presentation of

poststreptococcal glomerulonephritis (GN).

2. Nephrotic Syndrome: Characterized by heavy proteinuria (more than 3.5 g/day),

hypoalbuminæmia, severe œdema, hyperlipidæmia and lipiduria.

3. Asymptomatic hæmaturia or proteinuria; usually a manifestation of mild glomerular

disease.

Acute renal failure; characterized by oliguria or anuria and azotæmia. It can result from

glomerular injury, interstitial injury or acute tubular necrosis.

Chronic renal failure; characterized by all symptoms and signs of uræmia.

Urinary tract infection (UTI); characterized by bacteriuria and pyuria.

7. Nephrolithiasis; renal stones.

Glomerular Diseases:

4. 5. 6. The glomerular capillary wall consists of:

1. 2. A thin layer of fenestrated endothelial cells, 70-100 nm in diameter.

A glomerular basement membrane (GBM), with a thick central layer (lamina densa) and

a thinner electron-lucent layers (lamina rara interna and lamina rara externa).

3. The visceral epithelial cell (podocytes) having several foot processes interdigitating with

the lamina rara externa.

4. Mesangial cells; support the entire glomerular tuft, embedded within the mesangial

matrix.

The glomerulus is extraordinarily permeable to water and small solutes, but impermeable

to molecules of the size of albumin (70,000 Daltons) depending on the size and charge of the

molecule (the more cationic, the more permeable). The glomerular barrier function is largely

dependant on the integrity of the GBM, and the anionic proteins present within the wall and the

integrity of visceral epithelial cells (podocytes).

Pathogenesis of Glomerular Diseases:

Immune mechanisms underlie most cases of primary glomerulonephritis and many of the

secondary involvements. Four patterns of glomerular injury are categorized:

1. Deposition of soluble circulating immune complexes in the glomerulus (type III

hypersensitivity reaction). The antigen is not of glomerular origin, either endogenous

(e.g. SLE) or exogenous (e.g. after bacteria- streptococcal, viral- hepatitis B, parasitic-

P.falciparum and spirochetal- T.pallidum). Complexes are formed in the circulation, then

trapped in the glomeruli producing injury through binding to complement. By EM;

complexes deposit either in the mesangium, between the endothelial cells and the GBM

(subendothelial), or between the outer surface of the GBM and the podocytes

(subepithelial). With immunofluorescence against immunoglobulins and complement,

appear as granular deposits. Immune complexes may be cleared by monocytes and

mesangial cells when the exposure to the inciting antigen is not sustained.

2. Immune complex in situ:

a. Antiglomerular basement membrane, creating a linear pattern of deposition on

immunofluorescence and crescentic glomerulonephritis on LM. Some times anti GBM cross

reacts with the basement membrane of the alveoli (Goodpasture’s syndrome).

b. Heymann’s Nephritis; results from reaction of antibodies with antigen complexes on

the podocytes appearing as diffuse granular pattern.

c. Antibodies reacting with previously planted nonglomerular antigens including cationic

molecules, DNA, bacterial products, large aggregated proteins (IgG) and immune complexes.

3. Cell mediated immune glomerulonephritis.

4. Other Mehanisms:

a. Epithelial cell injury: can be induced by antibodies to visceral epithelial cells,

toxins and cytokines.

b. Renal ablation glomerulopathy: Glomerulosclerosis can result as an adaptive

change in the unaffected glomeruli of the diseased kidney by the additional load

on the intact glomeruli.

Nephrotic Syndromes:

Causes:

I. Primary glomerular diseases:

Minimal change disease.

Membranous GN

Focal segmental glomerulosclerosis

Membranoproliferative GN

Others (IgA nephropathy…)

II. Systemic Diseases:

Diabetes Mellitus

Amyloidosis

SLE

Drugs (gold, penicillamin, heroin)

Infections (malaria, syphilis, hepatitis B, AIDS)

Malignancy (carcinoma, melanoma)

Miscellaneous (bee-sting allergy, hereditary).

Minimal Change Disease (Lipoid Nephrosis):

Is the most frequent cause of nephrotic syndrome in children. On light microscopy it is

characterized by normal appearance of glomeruli, on EM there is loss of visceral epithelial cells’

foot processes. The cells of the PCT appear heavily laden with lipids. The pathogenesis is

unknown. It appears as insidious selective proteinuria (albumin). More than 90% of cases respond

to short course corticosteroids, but proteinuria recurs in more than two thirds of patients. Less

than 5% develop chronic renal failure after 25 years.

Membranous Glomerulonephritis (Membranous Nephropathy-MGN):

Is a slowly progressive disease, seen between 30 and 50 years, characterized by the

presence of subepithelial immunoglobulin deposits. In about 85% of the cases the condition is

idiopathic. It could happen in association with known disorders (secondary): 1. Infections

(chronic hepatitis B, syphilis, schistosomiasis, malaria). 2. malignant epithelial tumours (lung,

colon, melanoma). 3. SLE. 4. Inorganic salt (gold, mercury). 5. Drugs (penicillamine, cptopril). 6.

Metabolic disorders (DM, thyroiditis).

Membranous GN is a chronic immune complex nephritis, antibodies react in situ to

endogenous or planted antigens. On light microscopy, there is diffuse thickening of the GBM.

Proteinuria is nonselective and does not usually respond to corticosteroid therapy. Around 40%

suffer progressive disease terminating in chronic renal failure after 2-20 years.

Focal Segmental Glomerulosclerosis (FSG):

Characterized by sclerosis affecting some glomeruli and involving only segments of each

glomeruls. This histological change can occur in four settings: 1. Associated with other known

conditions (HIV infection, heroin addiction). 2. Secondary to other forms of GN. 3. A component

of glomerular ablation nephropathy. 4. Primary.

Primary FGN account for 10% of all nephritic syndromes, its proteinuria is not selective,

the response to corticosteroid therapy is poor, at least 50% of patients develop end stage failure

within 10 years.

Membranoproliferative GN:

Accounts for 5-10% of cases of idiopathic nephritic syndrome. Microscopically, the

glomeruli are large and show proliferation of mesangial cells and infiltrating leukocytes. The

GBM is thickened, and the capillary wall shows a double contour (tramtrack) appearance on PAS

and silver stains. The prognosis of MPGN is uniformly poor.

Nephritic Syndromes:

Acute Proliferative (Post-streptococcal) GN:

Also called diffuse proliferative GN, typically caused by immune complexes, classically

developing in children 1-4 weeks after recovering from infection with group A β-hæmolytic

streptococcal infection, either pharyngitis or skin infection. It is triggered by deposition of

immune complexes. Under the light microscope, there is uniform increased cellularity affecting

all glomeruli, due to proliferation and swelling of endothelial and mesangial cells and

neutrophilic and monocytic infiltrate, with occasional thrombi and necrosis of capillary walls.

Under EM, there is subendothelial, subepithelial and intramembranous deposits of immune

complexes. Complete recovery occurs in most children. Less than 1% develop rapidly progressive

GN or chronic renal disease.

Rapidly Progressive (Crescentic) GN:

Is a characterized by rapid and progressive loss of renal function, associated with severe

oliguria. Histologically, there are crescents in most of the glomeruli, produced by proliferation of

parietal epithelial cells of the Bowman’s capsule and infiltration by monocytes and macrophages.

It can be subdivided into three types: type I (Goodpasture’s syndrome), which is due to the

presence of anti-GBM antibody with linear deposits of IgG and C3. Type II: which is due to

immune complexes, and could complicate poststreptococcal GN, SLE, IgA nephropathy and

Henoch-Schonlein purpura. Type III; also called paucimmne type due to the lack of anti-GBM

and immune complexes, usually associated with polyarteritis nodosa or Wegener’s

granulomatosis.

Ninety percent of patients with RPGN will require dialysis or renal transplantation.

IgA Nephropathy (Berger’s Disease):

Usually seen in children and young adults, with gross hæmaturia occurring after a non-

specific respiratory tract infection. It is the most common glomerular disease worldwide. It is

characterized by deposition of IgA in the mesangium. Histologically, the changes range from

normal glomeruli, or appearing as focal GN, diffuse mesangioproliferative GN or rarely

crescentic GN. The disease runs a benign course in children, and a slowly progressive course in

adults.

Diseases of Tubules And Interstitium:

Acute Pyelonephritis:

Is a common suppurative inflammation of the kidney and the renal pelvis, is caused by

bacterial infection. It is almost always associated with lower UTI. There are two routes by which

bacteria can reach the kidney; ascending and hæmatogenous. Ascending infection is usually

facilitated by partial outflow obstruction, resulting in vesicoureteric reflux and intrarenal reflux.

There is also increased risk with pregnancy, instrumentation of the urinary tract and DM. One or

both kidneys may be involved appearing grossly as discrete, yellowish raised abscesses on the

renal surface, widely scattered or limited to one region, appearing histologically as suppuative

necrosis or abscess formation.

Chronic Pyelonephritis:

It’s a morphologic entity in which predominantly interstitial inflammation and scarring of

the renal parenchyma and scarring and deformity of the pelvicalyceal system. It can be divided

into two forms; obstructive and reflux-associated. The kidneys are not equally damaged.

Microscopically, there is: 1. uneven interstitial fibrosis with acute and chronic inflammatory cell

infiltration. 2. Dilatation or contraction of tubules with atrophy of the lining epithelium,

containing hyaline cass. 3. Vascular changes similar to hyaline or proliferative arteriosclerosis. 4.

The glomeruli are usually normal, some times showing features of focal segmental

glomerulosclerosis.

في الكتاب:Interstitial Nephritis

Acute Tubular Necrosis:

Is the most common cause of acute renal failure, characterized by destruction of tubular

epithelial cells. It could be classified according to the pathogenetic causative agents into: 1.

Ishæmic and 2. Nephrotoxic. ATN is characterized by necrosis of short segments of renal tubules,

mostly at the PCT and the thick ascending limbs of Henle’s loops. There is also proteinaceous

casts composed of Tamm-Horsfall proteins, hæmoglobin and other plasma proteins, associated

with interstitial œdema and interstitial inflammatory infiltrates.

Tumours:

Renal Cell Carcinoma:

Is an adenocarcinoma arising from renal tubular cells, representing 80-90% of all

tumours of the kidney and 2% of all tumours in adults. They are usually large at the time of

presentation. The cut surface is yellow-grey-white with prominent areas of cystic areas and

hæmorrhage. In advanced stages there is involvement of the renal vein, IVC, renal pelvis,

perinephric fat and adrenals. Histologically tumour cells may appear totally vacuolated (clear

cells) due to the presence of glycogen and lipids, or it may appear granular resembling the tubular

epithelium.

Wilm’s Tumour:

It is the third most common organ cancer in children under the age of 10. These tumours

contain a variety of cells derived from the mesoderm (immature glomeruli, tubules and

mesenchyme). It could be encountered as sporadic and familial cases.

Transitional Cell Carcinoma:

The entire urinary collecting system from the renal pelvis to the urethra could be affected

by this tumour. The urinary bladder is the most common location, ranging from small benign

papillomas to large invasive cancers. Papillomas are small frond like structures having delicate

fibrovascular cores covered by multilayered transitional epithelium. They rarely recur after

excision. Transitional cell carcinomas range from papillary to flat, noninvasive to invasive, and

extremely well differentiated to highly anaplastic. Squamous cell carcinomas also could be

encountered in the urinary bladder.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers essential kidney functions, including the excretion of waste and regulation of body balance. It also delves into the classification of renal diseases based on their location and clinical manifestations of such diseases. Assess your knowledge of major renal syndromes and their characteristics.