5.02 Approach to Px w/ Renal Disease and Urinary Abnormalities

Question 1

During transplant, where is the new kidney transplanted?

Answer 1

Since the diseased kidney is not removed, the new kidney is transplanted near the iliac fossa/inguinal area so it can be palpated easily.

Question 2

1. How thick is the cortex?
2. If you see in UTZ, cortex is less than #1 in terms of thickness, what do you think of? What else do you expect to see if you suspect this condition?

Answer 2

How thick is the cortex? 1 cm

If you see in UTZ, cortex < 1 cm thick, what do you think of? Think of CKD leading to scarring. Chronic dse is also marked by lack of clear differentiation between cortex and medulla.

Question 3

1. Which part of the kidney is very sensitive to toxic injury? Why? This part is also the site of action of w/c drugs?
2. Site of stone formation where urine drains before going to the renal pelvis.
3. Primary sites of obstruction (2)

Answer 3

1. Medulla (renal pyramids) because it contains the tubules. Site of action of diuretics (act on tubules).
2. Calyces
3. Hilus and pelvis

Question 4

1. Weight of kidney (% of one’s body weight)
2. Decreased CO is one of the leading causes of acute kidney injury. Why?
3. Each kidney is usually drained by how many arteries and veins?

Answer 4

1. 115 - 175 gm (0.5% body weight)
2. Because 25% of CO is received by the kidney. It is heavily dependent on good blood flow and thus, is very prone to ischemic injury. Shock states can also cause AKI.
3. One artery and one vein.

Note: Anything that causes a drop in CO, hypotension, and alterations in myocardial contractility may affect the kidney.

Question 5

1. What is the functional unit of the kidney?

2. How many #1 do our kidneys have? If this value is reduced to 50k or you only have 1 kidney, will you survive?

Answer 5

1. ) Nephrons.

2. ) 2 - 4 million nephrons. Yes, still compatible and NO need for dialysis as long as you take care of that one kidney.

Question 6

Function of:
1. Glomerulus

2. PCT
3. DCT
4. CD
5. LoH

Answer 6

Function of:

1. Glomerulus
   - “Guardians of the nephrons”
   - Ultrafiltration (keep cells and proteins in AND lets smaller molecules or ions out)
2. PCT
   - Bulk recovery of useful filtered substances (e.g. glucose, amino acids, K+, HCO3-, Na+)
   - EPO is produced in the interstitium w/c is impt for RBC maturation
3. DCT
   - “Fine tuning”
   - Na+/K+ via aldosterone, urinary acidification
4. CD
   - Regulates volume and conc
   - Under the ctrl of ADH
5. LoH
   - Creates medullary hyperosmolality
   - Na+/Cl- pumping

Question 7

3 main functions of the kidney

Answer 7

EHE

Excretory
-Excretion of xs water and metabolic waste products in urine

Homeostatic
-for maintaining fluid, electrolyte, acid-base balance

Endocrine

• Renin, EPO, TPO, Vit D3 (calcitriol), PGs
• It is only in chronic renal failure when endocrine dysfxns of the kidney become evident.

Question 8

Primary metric for kidney “function”?

Can it be used to assess acute kidney dse?

Answer 8

Primary metric for kidney “function”? GLOMERULAR FILTRATION RATE (GFR)
-Rate in mL/min that substances are filtered through kidney’s glomeruli

Can it be used to assess acute kidney dse?
-NO. It is measured in steady state.

Question 9

For a marker’s clearance to be EQUAL TO GFR and be considered a “STANDARD”, what criteria must it fulfill?

Answer 9

ALL OF THE FF:

1. Free filterable across the glomerular membrane
2. Neither reabsorbed nor secreted by the renal tubules
3. Neither synthesized nor metabolized in the kidneys

FRP

If these criteria are satisfied, then filtration rate (GFR) x plasma concentration (Px) = amount filtered AND the amount excreted in the urine, since there is no net gain nor loss

Question 10

GFR Formula and normal values

Answer 10

GFR = (Ux)(V)/Px = Cx

Normal Values:
Men - 125 mL/min (Range: 90-125)
Women - 110 mL/min (R: 80-120)

Newborns: 50% above adjusted for size

Above 40 yrs GFR declines by 1 mL/min per year

Question 11

Methods of Measurement/Standards

1. Inulin
   - Advantages and disadvantages
2. Iohexol
   - Advantages and disadvantages
3. Creatinine
   - Advantages and disadvantages
   - Is this highly variable throughout life? What can make it increase?

Answer 11

Methods of Measurement/Standards

1. Inulin
   - Adv: GOLD STANDARD for measuring GFR (totally filtered and neither reabs nor secreted)
   - Disadv: Impractical to use due to high cost and v labor intensive
2. Iohexol
   - Not the gold std but same adv and disadv as Inulin
   - Not totally filtered?
3. Creatinine
   - Surrogate to estimate GFR
   - Derived from ms metabolism of creatine
   - 10% secreted by the tubules = OVERESTIMATION OF GFR
   - Remains fairly constant throughout life
   - Can INCREASE acutely from ingestion of cooked meat

Question 12

GFR measurement: 1st method: Creatinine clearance

How?

Formula?

Interpretation?

Answer 12

Creatinine clearance
-Need 2 samples:
>1st sample: Timed urine sample (24 hrs or 1440 mins) - creatinine clearance is measured from urinary creatinine excretion rates for a defined period and is expressed in mL/min.
>2nd sample: Plasma sample - collected at the middle of urine collection period.
-Creatinine excretion by the kidneys is equal to creatining release from the muscle and is constant under most conditions. Thus, creatinine is a good substitute.

Formula:
GFR = Ccr = (Ucr x Vcr)/Pcr

Interpretation:
If: High P crea, low urine crea
-Incomplete urine collection (Men Urine cr = 20 -25 mg/kg; Women Urine cr = 15 - 20 mg/kg)
-Drugs w/c block tubule secretion of crea (trimethoprim, cimetidine, probenecid,amiloride, spironolactone, triamterene)
-Low creatinine production: Small ms mass or muscle wasting d/o & malnutrition

Question 13

Given: 50 kg female w/ ff 24-hr urine values:
TV = 1500 mL; Ucr = 60 mg/dL
Is the urine adequate?

Answer 13

Yes, urine collection is adequate as it falls w/in the calculated range of 750 - 1000 mg.

(900 mg)

Question 14

A 23 yr old med student (55 kg) collects her urine for 24 hrs and has blood drawn:
Serum crea = 0.6 mg/dL
24-hr urine vol = 2L (20 dL)
Urine creatinine = 50 mg/dL (inferred)

Is her kidney fxn normal?

If her serum creatinine is 1.2 mg/dL, is kidney fxn still normal?

Answer 14

Calculate Ccr in mL/min.

Question 15

1. Normal values of serum/plasma creatinine?

2. Plasma creatinine is used to ascertain what parameter? Relationship?

Answer 15

1. NV:
   Male: 0.8 - 1.3 mg/dL

Female: 0.6 - 1.0 mg/dL

*considered muscle mass and diet

2. Used to ascertain GFR
   Creatinine clearance = Cr production
   Thus, GFR x Px is constant

Since excretion is constant, Pcr is INVERSELY RELATED to GFR. Thus, the higher the Pcr, the worse the kidney fxn. Note that this is not a 1:1 relationship. Even if creatinine is just 2, there is already a 50% decline in GFR while a large decrease in GFR only manifests as a small increase in Pcr (only reduced when GFR declines by 50%). It is quite an INSENSITIVE MARKER.

Question 16

How to calculate GFR using Cockroft and Gault formula?

*For kidney fxn determination

Answer 16

GFR = Ccr = [(140 - age in yrs)(wt in kg)] / (72 x Pcr in mg/dL)

Note: Use LEAN body weight in calculation. Not wet weight.

Question 17

1. What do you use to assess effect of dietary restriction and BP control on progression of renal disease? Problem?
2. Best formula in assessing eGFR of Filipinos?
3. Limitations of creatinine-based estimates of eGFR?
4. What conditions can mask significant changes in GFR due to small changes in Pcr.

Answer 17

1. Modification of Diet in Renal Disease study (MDRD) Formula. Problem: Tends to underestimate GFR for near-normal creatinine
   - 6 value formula: age + race + gender + Pcr + albumin + BUN
   - 4 value formula: age + race + gender + Pcr
2. CKD-EPI formula: more closely correlated with GFR based on local studies using nuclear scans
3. Based on the ASSUMPTION that the px is in a steady state. For MRDR, not as good correlation when GFR > 60 mL/min/1.73m^2.
4. Gradual loss of ms from chronic illness, Malnutrition, Chronic use of GCs
   - Meaning for example if you have an in-px who is already having dec urine output, surprisingly you noted that the serum crea is only slightly elevated (onti lang tinaas niya) then when you check px again, oo nga pala. It’s bc px is malnourished. These will be the ff scenarios where these would give you slight only small changes in plasma Cr but in truth, you already have a v decreased GFR.

Question 18

Basic components of Renal Function

Answer 18

1. Glomerular Filtration
   (glomerular capillaries -> tubules)
2. Tubular Secretion
   (vasa recta -> tubules)
3. Tubular Reabsorption
   (tubules -> peritubular capillaries)

Question 19

Remember!

Answer 19

Anything:

Excreted = Filtered + Secreted - Reabsorbed

Question 20

How do we collect urine?

Answer 20

1. First, instruct px that he has to have a FULL BLADDER.

2.
Females: Cleanse periurethral area and hold labia wide apart to avoid contamination by vaginal secretions.

Males: Retract the foreskin and cleanse the prepuce around the urethra with water.

3.
First 200 mL -> Discard
A MIDSTREAM SAMPLE is taken w/o interruption or urinary stream.

4.
If having difficulty, catheterized sample should be taken. For children, can do needle aspiration.

5.
Examine specimen WITHIN 30-60 mins of voiding. (to avoid contam and to appreciate urine sediments better)

Note: What if px has indwelling catheter? It has been there for days. So if this is the case, instruct px to remove catheter and replace w/ a new one. After replacement, that’s the time you will collect the urine.

Question 21

Features of Nephrologic Syndrome: Disturbances in Urine Volume

1. Anuria
2. Oliguria
3. Polyuria
4. Frequency

Answer 21

1. Anuria
   - x < 100 mL/day (almost no urine output; a-, -uria)
   - Obstruction to poor renal perfusion
   - NOTE: 30 mL/hr is the obligate amt of urine that should be produced per day
2. Oliguria
   - x < 400 mL/day
   - Max urine osmolarity is 1200 mOsm/day
3. Polyuria
   - x > 3L/day
   - Commonly caused by diabetes insipidus or mellitus
4. Frequency
   - Increase in the number of urination unlike polyuria w/c denotes volume

Question 22

How do we evaluate polyuria?

Answer 22

First, confirm if it really is polyuria. Request for 24 hr urine output. If more than 3L = polyuria.

Next, check urine osmolality.
If more than 300 mOsm (despite big volume), solute diuresis.
-Px probably has high conc of solutes in the body. So that’s why there’s solute diuresis like in the case of there’s uncontrolled DM bc of the glucose or even the use of mannitol, the use of radiocontrast dye or urea from high protein feeding, from medullary cystic dses, or even resolving acute tubular necrosis or those w/ resolving obstruction like in post obstructive diuresis, and the use of diuretics.

What if your px has urine osm of less than 250? So check. Go back to hx. Does px have low serum sodium? Check if px has 1’ polydipsia probably from psychogenic cause, from hypothal dse, or even intake of these drugs. If none, then probably px has diabetes insipidus. To check, request for vasopressin lvl or ADH lvl. If low, then px probably has central DI. If relatively high, then most probably baka nephrogenic DI meron siya.

Question 23

Features of Nephrologic Syndrome: Abnormalities in urine sediment

Hematuria
a. Hematuria

b. Isolated hematuria
c. Single urinalysis with hematuria
d. Persistent or significant hematuria
e. Hypercalciuria and hyperuricosuria
f. Glomerular hematuria

Answer 23

a. Hematuria
- defined as presence of 2-5 RBCs/HPF and can be detected by dipsticks
- arise anywhere along urinary tract
- divided into glomerular, renal (non-glomerular), or urologic etiologies

NOTE: Not everything red is blood.
-Remember that not everything that is red is blood
so go back and do good med hx to px. Does px take these kinds of meds? Ingested these kinds of food? Or has certain conditions that predispose him to have these metabolites? So check. Do a thorough check. Do a good hx taking.

b. Isolated hematuria
- Can be bleeding from the urinary tract
- Common causes: stones, neoplasms, TB, trauma, prostatitis
- Gross hematuria + blood clots = postrenal causes
- Hematuria + pyuria + bacteriuria = infection
- Now we move on to isolated hematuria. So when you say isolated hematuria, in the urinalysis, you can only see RBCs. There’s no protein, no WBC, no cast. Only RBC. This can be bleeding from urinary tract.

c. Single urinalysis with hematuria
- Common
- Can be from menstruation, viral illness, allergy, exercise, or mild trauma

d. Persistent or Significant hematuria
- x > 3 RBCs/HPF on 3 urinalysis
- Single urinalysis with x > 100 RBCs
- Gross hematuria
- Associated with significant or urologic lesions in 9.1% of causes

e. Hypercalciuria and hyperuricosuria
- Risk factors for unexplained isolated hematuria
- Reducing calcium and uric acid excretion can eliminate microscopic hematuria (50-60% of px) e.g. via diet modification

f. Glomerular hematuria
- Dysmorphic RBCs seen by phase-contrast microscopy
- Isolated microscopic hematuria
- MOST COMMON CAUSES: IgA nephropathy, Hereditary Nephritis, Thin Basement Membrane Disease
- NOTE: Glomerulonephritis = hematuria + dysmorphic RBCs + RBC casts + protein excretion of more than 500 mg/day

Question 24

Criteria for glomerulonephritis?

Answer 24

Glomerulonephritis = hematuria + dysmorphic RBCs + RBC casts + protein excretion of more than 500 mg/day

Question 25

Evaluation of hematuria

Answer 25

If there’s hematuria, check if there’s presence of proteinuria (>500 mg/day) and presence of dysmorphic RBCs or RBC casts. If yes, then proceed ot the R part of this algorithm so can already request for serologic and hematologic evaluation and then sched px for kidney biopsy.

If none, check if px has WBC or WBC casts. If there is, then you can request for urine culture to rule out infection or urine eosinophils to rule out interstitial nephritis. If none, can proceed w/ the ff tests: hemoglobin electrophoresis, urine cytology, urinalysis (UA) of family members, and 24 hr urinary calcium/uric acid determination. So Hgb electrophoresis, maybe you are already considering a hematologic d/o causing the hematuria. Urine cytology to rule out malignancy. UA of fam members to check if they have hereditary nephritis or other hereditary GNs. Hyperuricosuria and hypercalciuria can be the risk factors for having microscopic hematuria. If none, can do IVP or renal ultrasound as indicated if there’s a stone or some blood circulation problems, you can do retrograde pyelography or arteriogram. If there’s a cyst, if there’s an indication, you can do cyst aspiration. If none, proceed w/ cystoscopy. If you found out that there is a bladder mass, you can do a biopsy. If none, you can do a kidney (renal) CT scan. If there’s a mass then you can proceed w/ biopsy. If none and you have exhausted all work-ups and didn’t find anything, you can always advise the px to have follow periodic UA. So this will be classified as asymptomatic urinary abnormality.

Question 26

Features of Nephrologic Syndrome: Abnormalities in urine sediment

a. Pyuria
b. Casts

Answer 26

a. Pyruria
- x > 5-10 wbc/hpf (10 if px is pregnant)
- Infection, inflammatory, or glomerular dse
- WBCs + bacteria = infection
- WBC + bacteria + WBC cast = pyelonephritis
- Remember not all the time bc of infection that px has pus or pyuria. There are certain conditions when they can also present w/ WBCs so in inflammatory states or even when they have glomer dses

b. Casts
- Cylindrical structures formed in the DCT and CD and present in the urine in certain disease states
- Brought about by the precipitation of Tamm-Horsfall mucoprotein and Albumin
- Pronounced in environments favoring protein denaturation and precipitation (low urine flow, concentrated salts, low pH)
- Generally, maintained their shape and composition as they pass through the urinary system

Question 27

Features of Nephrologic Syndrome: Abnormalities in urine sediment

Name the crystal and etiology, if possible.

1. Irregularly-shaped
2. Coffin-shape
3. Envelope- or rhomboid-shaped
4. Hexagonal
5. Fine, needle-shaped

Answer 27

Name the crystal and etiology, if possible.

1. Irregularly-shaped
   - Crystal: Urate
   - Etiology: Ammonium biurate, uric acid
2. Coffin-shape
   - Crystal: Triple phosphate
   - Etiology: Infection
3. Envelope- or rhomboid-shaped
   - Crystal: Calcium oxalate
   - Etiology: Most common
4. Hexagonal
   - Crystal: Amino acid (Cysteine)
5. Fine, needle-shaped
   - Crystal: Amino acid (Leucine)

*Not mentioned anymore: Sulfonamide

Question 28

Features of Nephrologic Syndrome: Proteinuria

a. Values:
- Normal urine protein excretion
- Normal albumin excretion

b. How do we quantify proteinuria?
c. What is microalbuminuria
d. Selective vs. Non-selective
e. Glomerular vs. Tubular

Answer 28

a. Considered significant if x > 150 mg/day protein
Normal urine protein excretion: x < 150 mg/day
Normal albumin excretion: x < 30 mg/day

b. Quantifying proteinuria
Can be quantified by 24-hr urine collection, urine albumin-creatinine ratio, or urine electrophoresis

c. Microalbuminuria
- Hallmark of early renal dse
- Up to 300 mg albumin/day; dipstick can be negative

d. Selective vs. Non-selective
- Wrt albumin

e. Glomerular vs. Tubular
- Tubular protein excretion should NOT exceed 1g/day
- Glomerular if more than 3500mg/day such as in nephrotic syndrome

Question 29

Frothy urine in 24 hr urine collection is suggestive of?

Answer 29

Glomerular origin

Question 30

Urine albumin creatinine ratio (UACR)

Answer 30

UACR

• Ratio between two measured substances: urine albumin and urine creatinine
• Estimates 24 hr urine albumin excretion
• Albuminuria: x > 30 mg/g UACR = marker of CKD

Question 31

Different mechanisms of proteinuria

Answer 31

Overflow

• Inc plasma conc of free-filtered proteins
• Proteinuria: Bence-Jones

Glomerular

• Abnormality of the glomerular BM
• Proteinuria: Albuminuria

Tubular

• Dec tubular reabs of normal amts of filtered proteins
• Proteinuria: Beta-2 or Alpha-1 microglobinuria

Secreted

• only one among the four that is considered physiologic
• Protein renal origin
• Proteinuria: Tamm-Horsfall proteinuria

Question 32

How do we evaluate proteinuria

Answer 32

So again we use the urine dipstick and then later on we quantify by requesting for 24 hr urine collection or the 1st morning spot a-to-cr ratio. So if the albumin is around 30-300, we know px has microalbuminuria and these ff cond can bring abt microalbuminuria. But if px has 300-2500, check if px has RBCs or RBC casts on urinalysis. Then these are the conditions, the myeloma-associated kidney dse. And what if px has more than 3500 mg/day of protein spillage or albumin spillage, then px already has nephrotic syndrome. Check for present of RBC or RBC casts on urinalysis. As mentioned a while ago, if there’s RBC casts already, there’s an indication for us to do early kidney biopsy

Question 33

Features of Nephrologic Syndrome: Azotemia

• What is it?
• Two conditions that bring about this condition?

Answer 33

• Azotemia - reduction in GFR (have an elevated serum creatinine and BUN)
• Brought about by AKI and CKD

Question 34

Consequences of Nephron Injury
1. Nephron loss

2. Abn urine constituents
3. Selective tubule defects

Answer 34

Consequences of Nephron Injury

1. Nephron loss - leading to:
   a. dec EPO
   b. kidney size
   - Exceptions: DM nephropathy (normal sized in UTZ), amyloidosis, polycystic kidney dse
   c. inc single nephron glomerular filtration rate
   - overworked functional nephrons because they take over the diseased nephrons
   d. dec NH3 production
   - causing metabolic acidosis
   * Slide 68: Complications that may arise among px w/ CKD*
2. Abn urine constituents
3. Selective tubule defects
   - Polyuria (inapp response to ADH)
   - Hyponatremia (inability to conserve NaCl)
   - Renal tubular acidosis

Question 35

Clinical Manifestations of Nephron Injury

1. Hyperkalemia
2. Acidosis
3. Stone formation
4. HypoNa

Answer 35

Clinical Manifestations of Nephron Injury

1. Hyperkalemia - arrhythmias
2. Acidosis - Kussmaul breathing
3. Stone formation - pain when voiding
4. HypoNa - hypotension, seizure, neurologic

NOTE: Not all px w/ kidney damage should be put on salt restriction because some of them are salt-wasting.

Question 36

Major Nephrology Syndromes: Syndromes of Nephron Injury

A. Acute Nephritis (AN)

• Usual cause
• Prototype
• Hallmark
• Clues to dx

Answer 36

Major Nephrology Syndromes: Syndromes of Nephron Injury

A. Acute Nephritis (AN)
-Usual cause: Transient inflammatory dses of the glomeruli

-Prototype: Acute post-strep GN (1 wk hx of sore throat and/or 2-3 wjs hx of skin infection)

-Hallmark: Hematuria
AN = Nephritic hematuria + azotemia (dec GFR) w/ well-preserved tubule fxn

-Clues to dx:
Hematuria (blood- or tea-colored urine), dysmorphic RBC (“mickey mouse shaped” from the glomeruli), RBC cast, azotemia, oliguira, edema, HPN

Question 37

Major Nephrology Syndromes: Syndromes of Nephron Injury

B. Nephrotic Syndrome

• Usual cause
• Prototype
• Hallmark
• Clues to dx

Answer 37

Major Nephrology Syndromes: Syndromes of Nephron Injury

B. Nephrotic Syndrome
-Usual cause: 1’ or 2’ (e.g. Diabetes, SLE, HBV)

• Prototype: Minimal change disease (commonly seen in children, present w/ selective proteinuria mainly albumin)
• Hallmark: PROTEINURIA
• Clues to dx:
• x > 3.5 g proteinuria/day mainly albumin
• Hypoalbuminemia
• Pitting Edema
• Hyperlipidemia

Question 38

Major Nephrology Syndromes: Syndromes of Nephron Injury

C. Acute Kidney Injury
-Definition

Answer 38

For AKI network: 3 stages (measures serum creatinine and UO)

For Rifle Criteria
R - risk of renal injury
I - injury to the kidney
F - failure of kidney fxn
L - loss of kidney fxn
E - end-stage dse

Question 39

Major Disease Categories causing AKI

1. Prerenal Azotemia
2. Intrinsic Renal Azotemia
3. Postrenal Azotemia

Answer 39

Major Disease Categories causing AKI

1. Prerenal Azotemia
   - Incidence: 55-60%
   - Caused by: Acute renal hypoperfusion
2. Intrinsic Renal Azotemia
   - Incidence: 90% from ATN
   - Caused by: Acute diseases of renal parenchyma (ATN, etc.)
3. Postrenal Azotemia
   - Incidence: x < 5%
   - Caused by: Acute obstruction of the urinary tract

Question 40

Remember!

Answer 40

Abdominal compartment syndrome - increased intraabdominal pressure leading to ischemia and organ dysfunction.

Under prerenal azotemia etiology

Question 41

Most common form of intrinsic ARF?

Answer 41

Acute Tubular Necrosis

• Tubular injury that can be ischemic (50%), nephrotoxic (35%), or multifactorial (combination of the two)
• Note: Profound ischemic injury may result into bilateral cortical necrosis

Question 42

How to differentiate prerenal azotemia from intrinsic renal failure?

Answer 42

There is a need to differentiate prerenal azotemia from intrinsic renal failure or the ATN. The way to differentiate them, you have to use the ff indices. slide

BUN/Pcr ratio

• Prerenal Azotemia: x > 20:1
• Oliguric Acute Renal Failure (Intrinsic): x = 10-15:1

Urine Na:
Less than 20 = prerenal bc in prerenal, you’re trying to conserve all the fluids, all the Na in the blood in the body to establish or reestablish hemodynamic stability. Remember where Na goes, water follows so less than 20 solute.

Urine osmolality is more than 500. Ofc bc you’re trying to put out less vol of urine as much as possible. You will conserve as much fluid as possible to reestablish hemodynamic stability. So putting out concentrated urine.

Need to compute for FeNa or fractional excretion of sodium so usually the result is less than 1 for prerenal azotemia for those with intrinsic ATN, renal failure, usually more than 20
Fractional excretion of Sodium = (Una x Pcr x 100)/(Ucr x Pna)

Urine/plasma Cr ratio usually more than 40 if prerenal if intrinsic or ATN usually less than 20.

Or can simply check urinalysis for presence of hyaline or granular casts, probably px is still on prerenal stage but if you appreciate muddy brown cast, px is on ATN.
Why do you need to differentiate? Bc this will have an impact on the management. If px is already on ATN or intrinsic renal failure, you have to be more careful w/ hydrating px, more wary on using some medications.

Question 43

Remember!

Answer 43

If the obstruction is bilateral or obstruction is unilateral w/ a dysfxnal or absent contralateral kidney, renal failure manifests.

*If unilateral + fxning contralat kidney = plasma crea is normal or only mildly elevated.

Question 44

Major Nephrology Syndromes: Syndromes of Nephron Injury

Chronic renal failure

Answer 44

Major Nephrology Syndromes: Syndromes of Nephron Injury

Chronic renal failure
-Azotemia-uremia progressing over more than 3 months or years

Clues to dx:

• Bilateral small kidneys
• Broad casts
• Signs of renal osteodystrophy
• Half nail signs - nails w/ dark periphery and light center BUT this is not pathognomonic of CKF since it can be found in px w/ nutri deficiencies
• Ruger Jersey spine in renal osteodystrophy - alternate dense and rarefied bands on Xray

Question 45

Stages of CKD

Answer 45

Stage 1: eGFR >/ 90
*Px has normal GDR but w/ albuminuria!!

Stage 2: 60 - 89

Stage 3: 30-59

Stage 4: 15-29

Stage 5/ESRD: x < 15

Table showing the diff stages of CKD. Note that when we say stage 5, it’s also what we now as the end-stage renal dse, the eGFR is less than 15% so when you say eGFR = estimated GFR. So usually px will require dialysis or transplant and then when we check on stage 1, you can see that the GFR is still normal (more than 90) but what’s the catch? Px already has albuminuria so that’s why stage 1. Stage 4 - need to prep px for possible kidney replacement therapy e.g. hemodialysis, peritoneal dialysis, and kidney transplant. How do you prepare? For hemodialysis, ask px to get fistula so usually they undergo surgery to have a fistula. For those transplant, tell them to get a donor already. Note: that stage 3 is further subdivided in 3a and 3b based on the eGFR.

Question 46

Top 3 causes of End-Stage Renal Disease

Answer 46

Diabetic Nephropathy
Glomerulonephritis
Hypertensive nephrosclerosis

Question 47

Azotemia Evaluation

Answer 47

So we can eval by again: requesting for US and urinalysis. If on US you will see that the parenchyma of the kidneys are already small, you have a v thin cortex meaning less than 1, you have bland sediments or isosthenuria, most probably px already has CKD.
But on US if you saw that px has hydronephrosis, that means there’s an obstruction and there is a need to have this px to undergo urologic evaluation to relieve the obstruction. If there’s normal sized kidney parenchyma, then most prob px has AKI lang. Check UA, if normal urine but w/ oliguria, proceed w/ urine electrolytes to measure the FeNa. You need to request also for urine osmolality. FeNa <1, U osmo > 500 point to prerenal azotemic states; but if more than 1 FeNa and less than 350 U osmo, then px already has ATN.
Abn urinalysis, you saw muddy brown cast, ATN na yan.
What if there’s bacteria? Then px has pyelonephritis.
Presence of WBC, casts, eo then prob intersitial nephritis.
What if presence of RBCs lang - then check for blood circulation? Is the renal a. or v. occluded? If yes, you can check/verify that by requesting for angiogram.
If there are presence of RBC cast or proteinuria, again you have to do renal biopsy to check for GN and even vasculitis.

Question 48

Major Nephrology Syndromes: Syndromes of Nephron Injury

Tubule Defects

Answer 48

Major Nephrology Syndromes: Syndromes of Nephron Injury

Tubule Defects

• Manifestation depend on portion of tubules affected
• May be anatomic or fxnal

Clues

• Electrolyte d/o
• Polyuria
• Tubular proteinuria (normal less than 1g/day)
• Nocturia
• Signs of renal osteodystrophy
• Large kidneys (Polycystic renal dse)
• Renal transport defects

Question 49

Major Nephrology Syndromes: Syndromes of Nephron Injury

Asymptomatic Urinary Abnormalities

Answer 49

Major Nephrology Syndromes: Syndromes of Nephron Injury

Asymptomatic Urinary Abnormalities

• Manifestations: (+) casts, cells, submassive glomerular proteinuria
• Dx: BY EXCLUSION!! Manif but on work ups, doesn’t meet any category or any syndrome so this is a dx by exclusion so all other syndrome MUST BE ABSENT to dx this

Question 50

Major Nephrology Syndromes: Urinary Tract Syndromes

Obstruction

Answer 50

Obstruction
-Luminal Narrowing docu by X-ray, surg, or endoscopy

If upper tract

• Acute unilateral - no dec in UO bc nagwwork pa urinary tract
• Acute bilateral - Anuria/oliguria
• Chronic bilateral - hyperkalemia, RTA, or even nephrogenic DI; px who underwent radiation

If lower tract

• commonly seen in males with BPH
• Manif: slow stream, hesitancy, urinary retention, nocturia

Question 51

Major Nephrology Syndromes: Urinary Tract Syndromes

UTI

Answer 51

UTI

• Bacteriuria > 10^5 colonies per mL
• Clues to dx: Pyuria, leukocyte casts

Location
Lower tract (cystitis)
-Dysuria, frequency, and urgency, bladder tenderness

Upper tract (acute pyelonephritis)
-Flank tenderness

Question 52

Major Nephrology Syndromes: Urinary Tract Syndromes

Nephrolithiasis

Answer 52

Nephrolithiasis
-Difficulty in passage of urine due to urinary stones

-Radio Findings:
if w/ obstruction: cortex thinned out, dilated calyceal system, stones in calyces

-Tx: surgical removal of stones

Types of stones:
Calcium Oxalate - most common stone
Uric Acid stone - lamellated inner core, dissolved in alkalinized urine
Cystine stone - found in urinary bladder and may cause hydronephrosis

Staghorn calculi

• seen in plain film KUB, fill the collecting systems, radiopaque, branched
• most difficult to treat
• causes severe hydronephrosis