Stefan G Kiessling MD FAAP Stefan G Kiessling, MD, FAAP To briefly - PowerPoint PPT Presentation

Stefan G Kiessling MD FAAP Stefan G Kiessling, MD, FAAP

 To briefly review the anatomy and physiology of the urinary system  To review the basics of urinalysis and urine sediment in children pertinent to a primary care provider’s needs children pertinent to a primary care provider s needs  To review normal and abnormal findings of the urinalysis and urine sediment and correlation with clinical pathology  To discuss a further diagnostic approach based on findings of urinalysis and microscopy

 Easy inexpensive tool to diagnose illnesses that could otherwise remain undiagnosed and to follow therapy response to certain diseases  Diabetes mellitus Diabetes mellitus  Glomerulonephritis  Hypertension related renal injury  Non ‐ symptomatic UTIs  Non ‐ symptomatic UTIs  AAP News 2010(12):31 ‐ UA should only be done in children at risk or with certain medical conditions but NOT used as a routine tool

 In the office setting, clean catch midstream voided specimen are collected most commonly specimen are collected most commonly  Make sure to label properly with name, MR#, DOB to avoid mix up with sample from another patient  Specimen should be examined within 30 minutes to 1 hour S i h ld b i d ithi i t t h after voiding either in the office or set to the lab  Collect new sample if >1 hr at room temperature or >4 hr in refrigerator f i t  Urine sediment should be reviewed in certain cases:  Spin 5 ‐ 10 ml of urine at 2500 ‐ 3000r/min for 3 ‐ 5 minutes  Discard the supernatant and resuspend sediment in remaining  Discard the supernatant and resuspend sediment in remaining amount of urine  Transfer one drop of urine to a slide and coverglass

Analysis Of The Urine Sediment Analysis Of The Urine Sediment y ► Take minimum of 8 Take minimum of 8 ‐ 10 cc of urine (if available); spin at 10 cc of urine (if available); spin at 2000 2000 ‐ 3000 3000 RPM for 3 RPM for 3 5 minutes with RPM for 3 ‐ 5 minutes with RPM for 3 5 minutes with > 5 RBC/HPF 5 minutes with > 5 RBC/HPF 5 RBC/HPF 5 RBC/HPF ► Discard supernatant and Discard supernatant and resuspend resuspend pellet in remaining urine pellet in remaining urine ► Put the cover glass on in Put the cover glass on in an an angle so that possible casts get washed to angle so that possible casts get washed to the opposite side the opposite side the opposite side the opposite side Casts ► If there is microscopic hematuria on an initial clean catch urine, If there is microscopic hematuria on an initial clean catch urine, repeat at least one more repeat at least one more time 2 time 2 ‐ 3weeks later 3weeks later since high (>50 since high (>50 ‐ 70) “false 70) “false positive” rate (Dodge et al., 1976) positive” rate (Dodge et al., 1976)

 Remember:  In adolescent and obese females, the labia must be spread apart to get a proper clean sample – MOST girls don’t do that  Eileen Brewer (Peds Nephrologist at Baylor) : Eileen Brewer (Peds Nephrologist at Baylor) :  Her husband urologist says that if your hands are not wet after you collect the sample, you did not do it right  Do not squeeze the diaper in infants except if you look for  Do not squeeze the diaper in infants except if you look for protein  Uncircumcised male with difficult to retract foreskin: Best method of collection is suprapubic tap  Consider In/Out cath

 Clear  Cloudy  Color (red/brown/yellow)  Smell

 Yellow: normal  Amber to reddish brown:  RBC – hemoglobin – myoglobin – hemosiderin  Bright red: Bright red:  Fresh blood, urates (infant diapers), porphyrins, pyridium, adriamycin, food coloring, beets  Brown ‐ Black: Brown Black:  Alkaptonuria, melanin, methyldopa  Bright orange:  Rifampin  Rifampin  Dark orange:  Bilirubin, carotin Brewer E.

 Ammonia: bacteria  Fruity: ketones (DM, starvation)  Maple Syrup: maple syrup disease  Musty: PKU  Ingested foods: asparagus  Excreted Drugs: antibiotics E t d D tibi ti

 Should be read as soon as dipstick is taken out of urine specimen  Alkaline pH due to loss of volatile gases (conversion of urea to  Alk li H d t l f l til ( i f t ammonia in the presence of bacteria and loss of CO 2 )  Range quite wide from 4.5 to 7 in normal individuals but usually acid (5 ‐ 6); needs to be acidic given need for excretion of daily id ( 6) d t b idi i d f ti f d il acid load of 2mEQ/kg/day  Usually of little importance  pH>7.5 in vegetarian (vegan) diet or urease producing organisms (Proteus; nitrite usually also positive)  Urine pH below 5.3 in the setting of metabolic acidosis, if not, think about RTA  Excess urine runover from protein reagent can falsely lower urine pH

 Range seen usually is between 1.003 and 1.035  Reflects number and size of particles in solution  Expected value:  Low in volume loading and high in volume deficit both reflecting L i l l di d hi h i l d fi i b h fl i appropriate tubular function  Unexpected value:  Low SG in ARF or oliguria reflecting tubular dysfunction

 Normally not seen unless serum glucose passes renal threshold (>180mg/dl)  Dipstick is specific for glucose (need other testing for galactose fructose lactose) galactose, fructose, lactose)  Not a good indicator for diabetes control  Glucose in the urine does not always reflect hyperglycemia G y yp g y but can be a sign of abnormal tubular reabsorption (need concomitant serum glucose to rule out renal glucosuria)  False positive in the presence of bacteria, Vitamin C and F l i i i h f b i Vi i C d ASA (acetylsalicylic acid)

 Normal in children as a rule of thumb is <100mg/day  Normal small amounts are either filtered by the glomerulus  albumin or secreted by the tubule  Tamm Horsfall secreted by the tubule  Tamm ‐ Horsfall  Dipstick tests ONLY for albumin  Urine albumin concentration influenced by rate of protein excretion and urine volume  In case of concerns of non ‐ glomerular proteinuria, need to consider special testing (Beta2 ‐ microglobulin, sulfosalicylic acid precipitation)  Dipstick:  0: 0 mg/dl  0: 0 mg/dl  Trace: 1 ‐ 10 mg/dl  1+: 15 ‐ 30 mg/dl  2+: 40 ‐ 100 mg/dl  3+: 150 ‐ 350 mg/dl  4+: >500 mg/dl

 < 1 g per day  Transient – postural – tubular – glomerular Transient postural tubular glomerular  > 3 g per day  Glomerular  False positive results  Macroscopic hematuria  Pyridium (phenazopyridine) y (p py )  Urine pH >8  Vaginal secretions  chlorhexidine chlorhexidine

 Normal < 3 RBC per high power field (HPF)  Results are trace to 3+  Results are trace to 3+  Positive dipstick does not exclude pigmenturia  true hematuria needs to be confirmed by RBCs on t ue e atu a eeds to be co ed by R Cs o urine microscopy  Can spin urine down – if supernatant clear  hematuria  Can originate from anywhere in the urinary tract  RBC morphology can help to determine glomerular RBC morphology can help to determine glomerular vs. non ‐ glomerular hematuria

 False positives:  Betadine, hypochlorite cleansers (oxidize dip ‐ stick reagent)  Other chemicals  Positive dipstick without RBCs ‐ > dilute urine (SG<1.006) leading to p ( ) g red cell lysis  Excess bacterial peroxidase in urine, bacterial overgrowth  Menstruating female g  Take home message : A positive dipstick for blood should always be followed by the assessment for presence or absence of red blood be followed by the assessment for presence or absence of red blood cells

 Product of fat metabolism (largely β hydroxybutyric acid but  Product of fat metabolism (largely β‐ hydroxybutyric acid but also acetoacetic acid and acetone)  Dipstick only detects acetoacetic acid and acetone thus p y underestimating true ketone excretion  Positive in DKA, starvation, anorexia, dieting, vomiting  Reported as trace to 4+ d  Caveat:  false negative in delayed reading of the urine sample  false negative in delayed reading of the urine sample  False positive in highly pigmented urine, mesna and levodopa metabolites

 Reported as 1+ to 3+  Reported as 1+ to 3+  May indicate abnormal liver function tests or biliary obstruction  Is quite unstable and should be read in a timely fashion to avoid false negative reading  Also false negative in presence of Vitamin C l f l f

 Degradation product from bilirubin formed by intestinal  Degradation product from bilirubin formed by intestinal bacteria  Trace amounts are considered normal since <5% of urobilinogen is excreted in the urine (1 ‐ 4mg/24hr) bili i t d i th i ( / h )  Presence can indicate hemolysis, intestinal obstruction or abnormal LFTs but not biliary obstruction y  If dipstick is positive for bilirubin but negative for urobilinogen, think about biliary obstruction (absence of bilirubin in the intestine, no bacterial metabolism) bilirubin in the intestine, no bacterial metabolism)

 Dietary nitrate is normally excreted in the urine  Dietary nitrate is normally excreted in the urine  Useful as a screen for presence of bacteria (if there is adequate contact time), usually gram negative rods which q ) y g g reduce nitrate to nitrite  False negative results in the presence of Vitamin C, yeast or gram positive bacteria and in vegetarians (low nitrate iti b t i d i t i (l it t production)