Urinary system Pathophysiology

What is urolithiasis/urinary and renal calculi?

Excess mineral forms stone out of crystalline particles

What are two contributing factors to the formation of urinary and renal calculi?

Low urine volume and urinary pH (changes solubility of stone forming chemicals)

What are the four chemicals in urine which inhibit crystallisation of minerals?

Citrate

Glycosaminoglycans

Pyrophosphate

Nephrocalcin

What are the four main types of urinary stones?

Calcium/phosphate

Uric acid

Sycstine

Struvite

What causes calcium phosphate stone formation?

Acidification of urine reduces calcium solubility

Calcium excretion rises if nephrons are naturally unable to resorb

Excessive calcium Resorbption

What causes uric acid stone formation?

High levels of purine (breakdown)

Purine found in alcohol and meat

Not soluble in acidic fluids

What causes cystine stone formation?

Cystinuria (disorder causing excessive loss of cystine)

Insoluble in acidic urine

What causes struvite stone formation?

Insoluble in alkaline urine

Associated with repeated urinary tract infections

Aka. Staghorn calculi

What are the two main types of bladder tumours?

Transitional cell carcinomas

Solid tumours

What are transitional cell carcinomas?

Arise from transitional epithelium

Benign

Stalk of fine branching fronds

Aka. Papillomas

What are solid bladder tumours?

Malignant

Invade bladder walls

May ulcerate and cause haemorrhage and necrosis

Why do 90% of bladder tumours start in transitional cell lining?

Lining is exposed to carcinogens excreted in urine

What is the appearance of transitional cell carcinomas?

Finger like projections

May penetrate basement membrane and grow into muscle of bladder walls

What are the characteristics of squamous epithelial cells?

Associated with chronic inflammation

What are two tumour suppressor genes which commonly suffer mutations and what do they do?

GSTM1 is responsible for enzyme glutathione S transferase

NAT2 is responsible for enzyme acetyltransferase

What are the characteristics of renal tumours?

Rare

Commonly renal adenomas

What are the origins of renal cancers?

Majority originating from nephron epithelial lining

Minority from collecting duct etc.

What is the commonest kidney malignancy and what is the origin?

Renal cell carcinoma

Arises from the epithelial lining of the proximal convoluted tubule

Which gene mutation contributes the most to renal cell carcinoma?

VHL on chromosome 3