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Showing posts with the label Nephrology

Emphysematous pyelonephritis - Review

  DEFINITION  Emphysematous pyelonephritis is an acute necrotizing infection characterized by gas formation. It is characterized by the presence of gas in and around the kidney.   ETIOLOGY   E. coli (58%) and K. pneumoniae (21%) are the organisms most commonly isolated. Clostridium and Enterobacter spp may also be responsible, 7% each.   RISK FACTORS   1) Diabetes mellitus (70-90%)- usually patients with poor glucose control. High levels of glucose in the urine serve as a substrate for these bacteria and large amounts of gas are generated through natural fermentation 2) Obstruction (25-40%)- it is another common predisposing factor for emphysematous pyelonephritis. For non-diabetics, protein fermentation is a proposed source of gas formation.  CLINICAL FEATURES  7% of cases may be asymptomatic. If symptomatic, patients may complain of pneumaturia, irritative lower tract voiding symptoms, flank pain or may present in a severe septic condition with an acute abdomen and hig

Arteriovenous fistula - AVF

Definition: It is an abnormal communication between an artery and a vein (or veins). It may be 1) a congenital malformation, 2) acquired by the trauma of a penetrating wound, 3) iatrogenic in which AVFs are created surgically in the arms or legs of patients undergoing renal dialysis. All arteriovenous communications have a structural and a physiological effect. Structural effect: The veins become dilated, tortuous and thick walled (arterialised). Physiological effect: There is high-pressure from the arterial system and an enhanced venous return/venous pressure. This results in an increase in pulse rate and cardiac output. The pulse pressure is high if there is a large and persistent shunt. Left ventricular enlargement and later cardiac failure may occur. A congenital fistula in the young may cause overgrowth of a limb. In the leg, indolent ulcers may result from relative ischaemia below the short circuit. Clinical features: Clinically, a pulsatile swelling or dilated to

Hemodialysis - when to start? / Calculation of normalized eGFR

Hemodialysis should be started when: 1) eGFR is < 6  mL/min/1.73  m 2 2) eGFR is < 15  mL/min/1.73  m 2   and patient is showing signs and symptoms of uremia, unable to control his hydration and blood pressure.  Cockcroft-Gault formula  is a very commonly used formula to get an estimate of the GFR. The unit for eGFR is  mL/min. The classification for stages of chronic kidney diseases  on the other hand is based on normalized eGFR i.e. the eGFR per 1.73  m 2  and the unit being mL/min/1.73   m 2 . Thus we also need to calculate the surface area of the patient's body. It is given by the formula as follows :  Body Surface Area ( m 2 ) = ( [Height(cm) x Weight(kg) ]/ 3600 )½ And the normalized eGFR ( mL/min/1.73   m 2 ) = (eGFR/BSA) x 1.73 A clinical example is given below.   A 45 year old man weighing 70 kg and 180 cm tall has been admitted to the hospital because of fluid overload. He has been treated for the past hours with diuretics but has not been im

Stages of Chronic Kidney Diseases

The table above shows how chronic kidney diseases are classified. Risk factors include hypertension, diabetes mellitus, autoimmune disease, older age, African ancestry, a family history of renal disease, a previous episode of acute renal failure, and the presence of proteinuria, abnormal urinary sediment, or structural abnormalities of the urinary tract. Stage 0 Not commonly included in many classifications but in this stage there is no kidney damage evident but patients have one or more risk factors mentioned above. Stage 1 Kidney damage is there demonstrated by persistent proteinuria, abnormal urine sediment, abnormal blood and urine chemistry, abnormal imaging studies but GFR i.e kidney function will be normal. Stage 2 Kidney damage is there and slight decrease in kidney funtion. Stage 3-5 The older term chronic renal failure corresponds to these stages. It is characterized by a progressive, significant and irreversible kidney damage with a GFR < 60 for 3 month

Comparison between normal / uremic plasma and dialyzing fluid

Cockcroft-Gault formula

It is a formula used to get an estimated creatinine clearance. It goes as follows: Creatinine clearance : mL/min Age : years constant : 1.23 for males, 1.04 for females normal range: men : 90 - 140 mL/min women : 80 - 125 mL/min