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Chat GPT MedBible > Renal > Flashcards

Renal Flashcards

1
Q

What is GFR?

A

The GFR is the rate of fluid transfer between glomerular capillaries and Bowman’s space.

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2
Q

What is the typical GFR, and how much of it is reabsorbed?

A

The typical GFR is approximately 90-120ml/min, but 99% is reabsorbed so 1-1.5L of urine per day

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3
Q

What are the two mechanisms of renal autoregulation?

A

The two mechanisms of renal autoregulation are myogenic regulation and tubuloglomerular feedback. (JGA)

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4
Q

How does myogenic regulation maintain GFR?

A

Myogenic regulation involves vasoactive factors released from endothelial cells, which lead to afferent arteriolar constriction and a decrease in GFR.

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5
Q

How does tubuloglomerular feedback maintain GFR?

A

Tubuloglomerular feedback involves the sensing of Na+ delivery to distal tubules by the macula densa, leading to afferent arteriolar constriction and a decrease in GFR.

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6
Q

What is the gold standard for measuring GFR?

A

Inulin clearance is the gold standard for measuring GFR, although it is rarely used in clinical practice.

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7
Q

What is the typical method for estimating GFR?

A

The typical method for estimating GFR is through serum creatinine concentration.

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8
Q

What is the assumption behind using serum creatinine for GFR estimation?

A

Serum creatinine is assumed to be freely filtered at the glomerulus with no tubular reabsorption.

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9
Q

How can GFR be estimated in clinical practice?

A

GFR can be estimated using formulas like Cockcroft-Gault, which use serum creatinine and demographic factors.

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10
Q

What are the limitations of serum creatinine measurement?

A

Limitations include the requirement for a steady state, a delayed response in acute kidney injury (AKI), compensation by remaining nephrons, and the influence of muscle mass.

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11
Q

What factors can affect serum urea concentration?

A

Serum urea concentration can be affected by dietary protein intake, catabolic rate (e.g., sepsis, GI bleed),

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12
Q

What can specific gravity in urinalysis indicate?

A

A decreased specific gravity (<1.010) suggests dilute urine, while an increased specific gravity (>1.020) suggests concentrated urine.

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13
Q

What does the presence of glucose in urinalysis suggest?

A

Glucosuria can suggest hyperglycemia, increased GFR (e.g., during pregnancy), or proximal tubule dysfunction.

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14
Q

What is the role of nitrites in urinalysis?

A

Positive nitrites suggest a UTI (e.g., E. coli), but this test has poor sensitivity and specificity.

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15
Q

What can the presence of ketones in urinalysis indicate?

A

Positive ketones may indicate conditions like alcoholic/diabetic ketoacidosis, prolonged starvation, or fasting.

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16
Q

What does the presence of hemoglobin in urinalysis indicate?

A

Positive hemoglobin can suggest haemoglobinuria (haemolysis), myoglobinuria (rhabdomyolysis), or true haematuria (RBCs seen on microscopy).

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17
Q

What are some examples of urinary casts, and what do they indicate?

A

Casts include hyaline casts (physiologic), RBC casts (glomerular bleeding), WBC casts (infection or inflammation), pigmented granular casts (ATN or acute GN), and fatty casts (heavy proteinuria).

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18
Q

What is the glomerulus, and what is its source of blood?

A

The glomerulus is a vascular structure composed of an anastomosing network of capillaries that arise from the afferent arteriole and drain into the efferent arteriole.

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19
Q

What are the components of the glomerular capillary wall?

A

The glomerular capillary wall consists of:
Fenestrated endothelial cells
Glomerular basement membrane (GBM)
Podocytes (with foot processes adherent to the outside of the GBM)
Mesangial cells in the mesangial matrix

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20
Q

What is the role of the glomerular capillary wall in filtration?

A

The glomerular capillary wall acts as a filtration barrier with selective permeability, which depends on the size and charge of filtering molecules. Podocytes play a key role in the barrier, especially for preventing the filtration of albumin.

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21
Q

How do we calculate GFR from Creatinine concentrations?

A

(Urine [Cr] x urine volume)/plasma [Cr]

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22
Q

What is the tubular reabsorption capacity for glucose?

A

9-11mmol/L! Start to have glycosuria.

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23
Q

What are the common risk factors for chronic kidney disease (CKD)?

A

Common risk factors for CKD include diabetes, hypertension, cardiovascular disease, nephrotoxic drugs (especially NSAIDs), autoimmune diseases, systemic infections (e.g., HBV, HCV, HIV), nephrolithiasis, lower urinary-tract obstruction, hyperuricemia/metabolic syndrome, acute kidney injury, family history of CKD, and age over 60 years.

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24
Q

Should clinicians screen patients for CKD?

A

Yes, clinicians should consider screening patients for CKD, especially those with risk factors such as diabetes, hypertension, and a family history of CKD.

25
Q

What tests are recommended for CKD screening?

A

For CKD screening, clinicians should arrange a mid-stream urine (MSU) sample and a blood test. These tests should include:
Urinary protein:creatinine ratio (PCR) or albumin:creatinine ratio (ACR)
Urine microscopy and culture
Serum creatinine and estimation of estimated glomerular filtration rate (eGFR)
Electrolyte levels (sodium and potassium)

26
Q

What should clinicians do if the initial proteinuria test is positive in investigating CKD?

A

If the initial proteinuria test is positive, clinicians should:
Consider factors affecting urinary protein excretion.
Confirm with another test 2 weeks later, preferably with a first morning void sample.

27
Q

Why is urine microscopy and culture important in CKD screening?

A

Urine microscopy and culture are important to check for haematuria, pyuria, and infection. If infection is present, the test should be repeated after treating the infection.

28
Q

Why is it recommended to repeat blood and urine tests if eGFR is low and the duration is uncertain?

A

It’s recommended to repeat blood and urine tests within a few days if eGFR is low and the duration is uncertain to ensure kidney function is not deteriorating quickly.

29
Q

Are dipstick tests for protein and cells in the urine alone sufficient for CKD screening?

A

No, dipstick tests for protein and cells in the urine alone are not recommended for kidney disease screening. If a dipstick is positive, it should always be confirmed with a laboratory sample.

30
Q

How is CKD defined?

A

CKD is defined as either kidney damage or a GFR (Glomerular Filtration Rate) less than 60 mL/min per 1.73 m² for more than 3 months.

31
Q

What are the two types of kidney damage that can define CKD?

A

Kidney damage can be either functional or structural.

32
Q

What are functional abnormalities that indicate CKD?

A

Functional abnormalities include proteinuria, albuminuria, and abnormalities of urinary sediment, such as dysmorphic red cells.

33
Q

What are structural abnormalities that indicate CKD?

A

Structural abnormalities can be detected through ultrasound scanning or other radiological tests.

Examples include polycystic kidney disease, reflux nephropathy

34
Q

How can clinicians estimate Glomerular Filtration Rate (GFR) and determine the stage of Chronic Kidney Disease (CKD)?

A

GFR = 186.3 × (serum creatinine in mg/dL)^(-1.154) × age^(-0.203) × (1.210 if the patient is Black) × (0.742 if the patient is female).

35
Q

How can clinicians determine if CKD is stable or progressive?

A

Progressive CKD is defined as a sustained decrease of estimated Glomerular Filtration Rate (eGFR) ≥ 5 in the previous year.

36
Q

What factors indicate a higher risk of developing end-stage kidney disease in patients with CKD?

A

Patients with progressive CKD, eGFR < 45, and/or nephrotic range proteinuria (urine Albumin-to-Creatinine Ratio > 250 or Protein-to-Creatinine Ratio > 300) have a higher risk of developing end-stage kidney disease, which may require treatment with dialysis or a transplant.

37
Q

What is the likelihood of needing dialysis or a transplant in patients without progressive CKD?

A

Patients who do not have progressive CKD are less likely to require dialysis or a transplant and can usually be managed in primary care with appropriate monitoring.

38
Q

What additional investigations are recommended for patients with CKD who have a urine Albumin-to-Creatinine Ratio (ACR) ≥ 30 or urine Protein-to-Creatinine Ratio (PCR) ≥ 50, and no history of diabetes complications or long-standing hypertension?

A

-Blood pressure
- Blood tests, including CBC (Complete Blood Count), iron studies if anemic, B12, folate, glucose, lipids, HbA1c, hepatitis B and C serology, ANA (Antinuclear Antibodies), anti-dsDNA (Anti-Double-Stranded DNA), and complement.

  • Calcium, albumin, serum protein electrophoresis, immunoglobulin levels, and serum-free light chains (SFLC) to exclude multiple myeloma.
39
Q

When should a renal tract ultrasound be considered for patients with a new diagnosis of CKD?

A

Consider a renal tract ultrasound if there is a new diagnosis of CKD with the following criteria:
GFR < 30
GFR < 45 with diabetes
GFR < 60 with evidence of progressive disease (eGFR decreased ≥ 5 in the previous year) and/or nephrotic range proteinuria (urine ACR > 250 or PCR > 300).

40
Q

How can the progression of CKD be retarded?

A

Treat the underlying condition that may contribute to CKD.
Implement aggressive management of hypertension (high blood pressure).
Implement aggressive management of diabetes mellitus (DM) if present.
Avoid nephrotoxic agents, especially NSAIDs (Nonsteroidal Anti-Inflammatory Drugs).

41
Q

What is the cause of renal anemia in CKD?

A

Renal anemia in CKD is caused by erythropoietin deficiency.

42
Q

At what eGFR levels does renal anemia typically become noticeable?

A

Renal anemia is noticeable at eGFR levels below 30, or below 40 for individuals with diabetes.

43
Q

What is the target Hb range for CKD patients with renal anemia based on clinical trials?

A

Based on large clinical trials, the target Hb range for CKD patients with renal anemia is typically between 100 and 120 g/dL.

44
Q

What should be ensured in CKD patients with renal anemia regarding supplements?

A

In CKD patients with renal anemia, it’s essential to ensure that they are replete in B12, folate, and iron.

45
Q

What are some potential causes of erythropoietin resistance in CKD patients with renal anemia?

A

Erythropoietin resistance in CKD patients with renal anemia can be caused by factors such as missed causes of anemia (e.g., GI bleeding), relative iron deficiency, non-compliance with treatment, hyperparathyroidism, marrow fibrosis, or pure red cell aplasia (PRCA).

46
Q

How is Chronic Kidney Disease (CKD) defined?

A

CKD is defined as either markers of kidney damage for ≥3 months (e.g., structural, imaging, laboratory) or a Glomerular Filtration Rate (GFR) <60 mL for ≥3 months.

47
Q

What are the common etiologies of CKD?

A

The common etiologies of CKD include diabetes mellitus, hypertension, glomerulonephritis, and others.

48
Q

What is the genetic cause of CKD?

A

Polycystic kidney disease

49
Q

How is CKD classified?

A

CKD is classified based on GFR and the degree of proteinuria.

50
Q

At what point does CKD become symptomatic?

A

CKD is typically asymptomatic until GFR drops below 30 mL.

51
Q

What are some pathological features associated with CKD?

A

CKD is associated with fluid retention, electrolyte and acid-base disorders, hypocalcemia, hyperphosphatemia, hyperkalemia, metabolic acidosis, azotemia, anemia of chronic disease, abnormal hemostasis, sex hormone dysfunction, and dyslipidemia.

52
Q

What are the primary treatment strategies for CKD?

A

Treatment involves controlling hypertension, managing diabetes mellitus, addressing reversible causes, making lifestyle changes, and using medical therapy to manage complications.

53
Q

What complications are associated with CKD?

A

Complications include acquired renal cystic disease in dialysis patients and cardiovascular complications, which are the most common cause of death.

54
Q

What are the clinical presentations and treatments of renal osteodystrophy?

A

Clinical presentations include bone pain, fractures, pruritis, neuromuscular irritability, and tetany.

Treatment includes dietary phosphate restriction, oral phosphate binders, calcium supplements, calcitriol, and surgery then cinacalcet for hyperparathyroidism.

55
Q

Indications for dialysis

A

Acidosis
Electrolyte disturbance
Ingestion of substances (overdose)
Overload (volume)
Uremia

56
Q

How does nephritic syndrome present?

A

Typically characterised as:
 Haematuria (with red cell casts)
 Hypertension / fluid overload
 Oliguria
 Proteinuria (<3.5g/24hr)
 Azotaemia
 Often reduced renal function

57
Q

Which GN present with nephritic features?

A

Anti-GBM mediated (+/- Goodpasture’s)
Immune mediated (IgA , SLE, membranoproliferative, Post-infectious GN)
Pauci Immune: ANCA +ve

58
Q

How does nephrotic syndrome present?

A

Typically characterised as:
 Proteinuria (>3.5g/24hr)
 Hypoalbuminaemia
 Oedema
 Hyperlipidaemia/hyperlipiduria (side-effect of  albumin production)
 Often normal renal function

59
Q
A

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