lab med test 3 lecture 16

B.The blood on the urine dipstick may be false-positive; follow up urine studies are required

A 35-year-old male is transported by EMS to the ER after being found trapped under his tractor. He reports the tractor tipping while he was sowing corn. His legs were trapped underneath the 600 lb tractor for 4 hours. He was catheterized by nursing staff and the output from the urinary catheter was coca-cola colored. A urine dipstick was positive for blood but was otherwise normal. Which of the following is definitively true?

A.Interventional Radiology should be consulted for drainage of a renal hematoma

B.The blood on the urine dipstick may be false-positive; follow up urine studies are required

C.Urine microscopy will reveal red blood cells

D.The patient needs to be placed on fluid restriction to allow renal rest

B.The leukocyte esterase is likely a false positive due to doxycycline use

A 23-year-old female is seen in the clinic for follow up evaluation of dysuria. She was seen in the urgent care 5 days ago and treated for a UTI with doxycycline. She took her last dose of antibiotic yesterday. She still describes some urinary frequency but reports she has been drinking a lot of water. You decide to obtain an UA to further investigate. It is positive for leukocyte esterase but is otherwise normal. A follow up urine microscopy is ordered which reveals no WBCs. Which of the following is most likely true?

A.The patient should be prescribed an alternative antibiotic for treatment of a UTI

B.The leukocyte esterase is likely a false positive due to doxycycline use

C.The urine microscopy is likely a false negative

D. Uric acid levels

A 54-year-old female with a past medical history of Type II Diabetes Mellitus and hyperlipidemia presents to the clinic for routine follow up. She has not been seen for over 2 years. Which of the following labs would NOT be appropriate?

A.Hemoglobin A1C

B.BMP

C.Urine Microalbumin

D.Uric acid levels

- urine culture and sensitivity

- random urine screening

- 24 hour urine

- first morning specimen

what are the types of urine specimens

- Performed if indications of Urinalysis (ex: leukocyte esterase, WBCs, nitrites)

- Must use "clean-catch" technique

what are some key factors for urine culture and sensitivity

- Cleanse urinary meatus with antiseptic

- Use sterile container

- Midstream catch

Clean catch technique

- Specimen of choice for drug screening

- No preparation needed

- No clean-catch needed

- Obtained at anytime during day

what are some key factors to random urine specimen

- Evaluate urine composition and volume over day period

- Quantitative study for hormones, glucose, proteins

- Kidney stone eval, nephrotic syndrome, accurate measure creatinine clearance

what are the factors associated with 24 hour urine

- Void before bed, collect specimen upon rising

- Most accurate surrogate for 24-hour-urine

what are the factors to define first morning specimen

- Quantitative measure of electrolyte content of urine (Calcium, Sodium, Potassium)

- Variable clinical utility (ex: Urine sodium aids in diagnostic eval of hyponatremia)

what do you look at for urine electrolytes

5-6.5

normal ph for urine

- estimation of solute concentration

- normal 1.016 - 1.022

- Affected by ADH and state of hydration

Specific gravity for urine test

- detects the presence of hemoglobin and myoglobin

- UTI, nephrolithiasis, cancer, etc

- Falsely positive in myoglobinuria (rhabdomyolysis, muscle disorders)

Blood in a urine dipstick

- normal is negative

- positive if blood glucose > 180 mg/dL, as in diabetes

glucose in a urine dipstick

- normal is negative

- produced from fat metabolism due to low carbohydrates

- diabetic ketoacidosis, starvation, vomiting

ketones in a urine dipstick

- normal is negative

- positive is due to bacteria converting urinary nitrates to nitrites - UTI (gram negative UTI)

nitrates in a urine dipstick

if infection with gram positive bacteria, pt is a frequent voider

why do false negatives show for nitrates in urine dipsticks

- normal is negative

- produced by WBC breakdown due to pyuria/UTI

leukocyte esterase in urine dipstick

due to vaginal discharge or menstrual blood, some medications (ex: doxycycline), systemic infections

why is there false positives with leukocyte esterase in urine dipstick

due to dilute urine, high level proteinuria or glucosuria, expired test strips

why is there false negatives with leukocyte esterase in urine dipstick

- normal is negative

- present with liver disease

bilirubin in urine dipstick

- present in very low amounts

- Increased with hemolysis, intestinal bacteria

urobilinogen in urine dipstick

- Normal = negative on urine dipstick

- increase in renal disease (diabetic nephropathy, hypertensive nephropathy, glomerulonephritis), exercise, seizures, pre-eclampsia

protein in urine dipstick

- urine dipstick

- urine microscopy

what are the two components to urinalysis

- Available as point of care

- Affordable

- Less Accurate (false positives and false negatives)- good initial screening

what components best describe urine dipstick

- Must be performed in lab

- More accurate

- Quantitative

what components best describe urine microscopy

- Suspected urinary tract infection

- Annual monitoring for proteinuria

- Renal disorders

- Evaluation of systemic disease

when would you preform a urinalyis

- Easy

- non-invasive

- relatively cheap

what are benefits for urinalysis

over-dilution of urine, drinking citrus fluids, OTC phenazopyridine, antibiotic use

how can false negatives occur in a urinalysis

- Cells

- Casts

- Crystals

- Bacteria or Yeast

Microscopic examination of urine to quantitatively determine the presence of:

Casts:

Clumps of material or cells that form in the renal tubules; take on shape of tubules

Pyelonephritis

WBC casts in

glomerulonephritis

RBC casts in

Gout

uric acid crystals

crystals

if this is found in urinary sediment, indicate that renal stone formation is imminent or present

stones

Crystals do not cause symptoms until they form _______, which can obstruct urinary tract

- Amphetamines

- Barbiturates

- Cocaine

- Marijuana (THC)

- MDMA

- Methadone

- Opiates

- Oxycodone

what do urine drug test typically identify

- Pre-employment screening

- Compliance to treatment regimen

- Athletes

when are urine drug test used to identify drugs in

RBCs

If dipstick + blood check for

WBCs or bacteria

If dipstick + leukocyte esterase or nitrites Check for

levels of albumin

what does urine microalbumin test for in urine that is not detectable with routine dipstick

lower life expectancy d/t CVD

within a urine microalbumin test, nondiabetics have an elevated urine microalbumin that correlates to

neuropathy

urine microalbumin can indicated earliest indication of

prior to decline in eGFR

When is nephropthy detected in urine mircoalbumin

yearly in patients with diabetes or hypertension

How often do you want to monitor nephropathy with a urine microalbumin yearly in patients with diabetes or hypertension

duration of disease and degree of glycemic control in diabetes

The amount of albumin in a urine mircoalbumin test is related to

Diabetics

_______ with elevated urine microalbumin have 5-10X increase incidence of CVD, retinopathy, and ESRD

- protein

- albumin

if the glomerulus is damage it will mostly cause an increase in what in the urine