Urinalysis

Question 1

Odor and Color

Answer 1

Bad odor = infection, bacterial colonization, asparagus!!!!

Cloudy = crystals, WBC, or chyluria

Color –> blood will turn it dark/red/coca-cola colored

Question 2

Specific Gravity

Answer 2

Tells us how CONCENTRATED the urine is

Isotonic: same specific gravity as blood = 1.010

Hypotonic: < 1.010

Hypertonic: > 1.010

Increased concentration of urine = higher specific gravity –> dehydration likely, compensate by concentrating urine

Question 3

SG examples

Answer 3

FLU and High fever, not much to eat or drink –> 1.035 would make sense (concentrated urine to compensate for not eating/drinking to maintain hydration status)

Flu, diabetes insipidus, usually makes 4-5 liters of urine, continued without being able to drink; feels weak, low BP, high HR –> 1.05 would make sense –> diabetes insipidus, CANT PRODUCE ADH – needs to conserve fluids but isn’t capable

4 glass of SWEET TEA for lunch with urinalysis 2 hours later –> 1.05 (drink a lot, excrete a lot)

Chronic kidney disease with a GFR of 20 ml/Min –> 1.010 (in order to concentrate urine, need healthy nephrons (not here!) so we get isotonic urine

Diabetes with blood sugar chronically 130 mg/dl and notes increased urine output –> 1.020 (tricky, there is an osmotic agent GLUCOSE in this case, so it’s hard to move water from tubules which might make us think that the urine would be isotonic, but the HIGH CONCENTRATION of glucose increases the tonicity of urine, making it hypertonic)

Question 4

If you get infused with HCl (acid) what happens to the urine?

Answer 4

IT WILL BECOME ACIDIC TOO!! If you put more acid in your body, it should mean more acid gets excreted

Question 5

Low Urine pH

Answer 5

If urine pH is low, there is a problem in the PCT with bicarb reabsorption –> if some bicarb is excreted in the urine, the BLOOD becomes acidic due to excretion of H+

Question 6

High Urine pH

Answer 6

Problem is due to an inability of the COLLECTING DUCT to secrete acid into the urine or to generate a proton gradient

Question 7

Ketoacids

Answer 7

Diabetic patients present with these in their urine

If body doesn’t have access to glucose, it will utilize fatty acids for energy metabolism –> produces ketone bodies; occurs in settings of diabetes (mainly type 1 where there is no insulin) and starvation

Question 8

Diabetics, Insulin and Ketoacidosis

Answer 8

In poorly controlled Diabetes type I, if a patient doesn’t take insulin, then their glucose will be super high. Low insulin leads to increased GLUCAGON production which leads to more glucose in the blood, and this spills into the urine –> it will take water with it, osmotic diuresis –> this leads to LOTS of urination and dehydration

Also, KETOACIDS are formed when there is no insulin to use an alternate form of energy (high blood glucose – glucose just doesn’t enter cells without insulin, so it is not used for energy)

Ketoacids are ACIDIC duh, bicarb isn’t enough and gets overwhelmed

DIABETIC KETOACIDOSIS

Question 9

What is the point of podocytes?

Answer 9

To keep large protein molecules out of the urine! If it is damaged, there will be protein in urination (nephrotic syndrome!!!) –> glomerulonephritis, renal neoplasms, UTI can cause this

Question 10

Fresh vs. Old sample

Answer 10

Fresh (healthy urine) –> 0-3 RBC, 0-5 WBC, no squamous cells, no transitional cells, no renal tubule cells, no casts, limited crystals, no bacteria

Older urine (but still healthy patient) –> hemoglobin but NOT RBC, or MANY BACTERIA WITHOUT WBC, or amporphous crystals

Also, if you have an infection (bacteria) then the bacteria will just grow and you won’t be able to tell how much there actually is and whether or not it needs treatment!

Question 11

Casts refresher

Answer 11

Cylindrically shaped and form from stuff that has filled up the tubules

Muddy Brown –> acute kidney injury

RBC casts –> NEPHRITIC syndrome

WBC casts –> pyelonephritis (also with flank pain and fever!) or interstitial nephritis

Epithelial cell casts – bigger than WBC and have a homogenous nucleus in the center of the cell or off to a side; seen with tubular injury or ACUTE KIDNEY INJURY

Epithelial casts + Muddy Brown = Acute Tubular Necrosis!

Question 12

Albumin/Creatinine Ratio

Answer 12

Normally Under 30

30-299 –> microalbuminuria

300+ –> macroalbuiminuria (high risk for ESRD, marker of renal disease progression, risk factor for CV disease)

Question 13

Salt excretion

Answer 13

WE EXCRETE AS MUCH SALT AS WE TAKE IN

1500 mg for a low-salt diet (uncontrolled HTN)

2300 mg for normal people

Question 14

Blood in urine

Answer 14

Blood from the urethra will appear in the first 15mL of urine and blood from the bladder in the final 10‐30mL.

Blood from the upper urinary tract will appear
throughout.