Cockcroft-Gault formula is used to estimate creatinine clearance rate using age, weight and serum creatinine level. It is named after the scientists who created the formula.
eCcr =
(140-age) * Weight (in kilograms) * 0.85 (if patient is female)
—————————————————————
72 * Serum creatine (in mg/dl)
Hence, the creatine clearance will be less in elderly individuals and females.

Renal cell carcinoma can occur in a patient with a solitary kidney
The current recommendation is to do partial nephrectomy as long as sufficient margin of normal tissue is available
This helps to avoid the requirement of lifelong hemodialysis
Partial nephrectomy cannot be done in those with a large tumour or multiple small tumours throughout the kidney
Survival rates of upto 90% have been reported in stage I disease and upto 76% for stage III tumours with conservative surgery

Reference:
Diagnosis and Management of Cancer By Ashok Mehta, S.C. Bansal

Diabetes glomerulosclerosis with nephrotic syndrome – histopathology
Click on image for an enlarged view

Nephrotic syndrome is characterised by albuminuria, hypoalbuminemia, oedema, hyperlipidemia and lipiduria
The increased loss of proteins in urine stimulates the liver to increase synthesis of proteins
Apolipoporteins are synthesised in increased quantities – especially apo B, apo C-II, and apo E which are used VLDL and LDL formation
Apoproteins associated with HDL synthesis – apo A-I and apo A-II usually remains normal
In addition to this, there is decreased lipid catabolism due to decreased activity of lipoprotein lipase
All these factors together contribute …

IV – 2-5 minutes
IM – 10-10 minutes
Oral – 20-40 minutes

Duration of action – 3-6 hours

Better diuresis
Less hypokalemia at equinatriuretic doses
Less hyperuricemia
Less hyperglycemia

It is a loop diuretic.
Mechanism of action

secreted into the renal tubule by the organic anion transporter in the proximal tubule
inhibits the Na+ K+ 2Cl- co-transporter in the thick ascending limb of loop of Henle by binding to Cl- binding site
increases local prostaglandin synthesis
weak carbonic anhydrase inhibitor

Actions in renal tubule:

abolish corticomedullary osmotic gradient
block positive and negative free water clearance (urine becomes isosmotic with plasma)
increases bicarbonate excretion and urine pH by inhibiting carbonic anhydrase
increases excretion of K+ (by increasing Na+ reaching the distal tubule)
increases excretion of Ca2+, Mg2+
decreases excretion of uric acid …

It is loop diuretic acting on Na+ K+ 2Cl- Co-transporter in thick ascending limb of loop of Henle.
Torsemide vs Frusemide

3 times more potent
better oral bioavailability
absorbed more rapidly when given orally
longer T1/2 (3.5 hrs)
longer duration of action (4-8 hrs)

Indications

Edema
Hypertension

Dose

2.5-5mg OD in hypertension
5-20mg/day in edema
upto 100mg BD in renal failure

Loop diuretics – also known as high ceiling diuretics or high efficacy diuretics – are drugs which inhibit  Na+ K+ 2Cl- transporters in the thick ascending limb of loop of Henle to increase production of urine. Eg: Frusemide, Bumetanide, Torasemide
Uses of loop diuretics:

Edema due to all etiologies – cardiac, renal, hepatic. 
Left ventricular failure – frusemide is given intravenously which acts as a pulmonary venodilator thus decreasing left ventricle preload, decreases venous return and blood volume by its diuretic action
Cerebral edema – can be combined with osmotic diuretics
Hypertension – indicated in …

Excretion of sodium in urine

Loop diuretics