14.1 Urinalysis Terminology

CMLA Work Area III (Examination / Analytical Considerations) is 83 items, or 41.5% of the 200-question exam. Urinalysis (UA) is competency 9. AMT III.9.A.1 is a terminology list: collection types, physical and chemical findings, and formed elements in sediment. Chapter 9 already taught how to instruct a patient. This section is the language you use when you look at the cup and the report. A Certified Medical Laboratory Assistant (CMLA) who can define each word can stop a look-alike trap before it is reported.

Quick Answer: Random, midstream, and clean-catch are not synonyms. Macroscopic UA is what you see plus chemical analyses (the reagent strip). Microscopic UA is the sediment. Specific gravity (SG) is concentration; a refractometer measures it. Pyuria is white cells; hematuria is blood; glycosuria is glucose; proteinuria is protein; polyuria is high volume. Casts form in tubules; crystals precipitate in urine; a skin contaminant is not infection. A dipstick is not culture and sensitivity (C&S).

Collection terms in UA language

Random urine is a single void at any time, without a timed start or stop. It is the usual specimen for a routine screen. Random does not mean dirty, and it does not mean midstream.

Midstream means the patient starts in the toilet, catches the middle portion, and finishes in the toilet. The first urine flushes distal urethral organisms and debris.

Clean-catch adds periurethral cleansing and a sterile cup, usually with midstream collection, so the specimen can support C&S. Clean-catch is a method, not a color. A random hat is not a culture specimen.

Timed collections—including 2-hour, 12-hour, and 24-hour—save all urine in a defined clock window. The complete volume is the specimen. Discard the first void, save every later void including the stop-time void, and send the entire jug (Chapter 9). In UA language, timed is not “a cup labeled 24-hour.”

Macroscopic versus microscopic

Macroscopic UA is the physical examination (color, clarity, sometimes odor and volume) plus chemical analyses on a reagent strip. You do not need a microscope for the strip. Color (straw, yellow, amber, red, brown, orange from phenazopyridine) and clarity (clear, hazy, cloudy, turbid) still belong on the report.

Microscopic UA is examination of sediment—the concentrated formed elements after centrifugation, or an equivalent automated particle method the laboratory validates. Cells, casts, crystals, organisms, mucus, spermatozoa, and junk live here.

Chemical analyses are the pad reactions: glucose, protein, blood, leukocyte esterase, nitrite, ketones, pH, SG, urobilinogen, and bilirubin (Section 14.2). They are screening chemistry, not a culture and not a species identification.

Confirmatory tests are follow-up methods the instructions for use (IFU) or standard operating procedure (SOP) require when a screen is positive or when the strip is not enough (tablet or precipitation tests such as Ictotest or sulfosalicylic acid, historically Clinitest). Confirmation is not “dip it twice and hope the color is prettier.”

Concentration, volume, and named “-urias”

Specific gravity is the density of urine compared with water (water = 1.000). It estimates how concentrated the specimen is. Very dilute urine can miss cells and chemicals; very concentrated urine can exaggerate them. Isosthenuric urine near 1.010 is a physiology clue, not a dipstick error by itself.

A refractometer measures refractive index and converts it to SG. Distilled water should read 1.000 before you trust a patient drop. Many clinical refractometers are temperature-compensated; still follow the SOP check. Dipstick SG is a different ionic method and is only an estimate. When the SOP says confirm SG, use the refractometer (or the laboratory’s designated meter), not a second glance at the strip. Radiographic contrast and some dissolved substances can raise refractometer SG more than the ionic pad—another reason the two methods are not interchangeable.

Polyuria is excretion of an abnormally large urine volume (classic adult teaching is more than about 2.5–3 L/day; always interpret with the clinical picture and the timed collection). It is a volume term. Pale color is not automatically polyuria, and a random cup does not measure 24-hour output.

Proteinuria is protein in urine. The strip is most sensitive to albumin. Some clinically important proteins (including certain light chains) may be missed on the pad and need a confirmatory precipitation method if the SOP uses one.

Glycosuria is glucose in urine. The glucose oxidase pad is specific for glucose, not every sugar. A pediatric reducing-substance question is a confirmatory-method question (Section 14.2), not a reason to rename the pad.

Hematuria is blood in urine, classically intact red blood cells. The blood pad detects heme, so free hemoglobin and myoglobin can also turn it positive. The microscope tells you whether intact red cells are present. A positive blood pad with no red cells is not “the strip is broken”; it is a different heme source until proven otherwise.

Pyuria is white blood cells in urine (pus). It suggests inflammation, often infection, but it is not a culture result and not every pyuria is bacterial urinary tract infection.

Ketones are products of fat metabolism (acetoacetate, acetone, β-hydroxybutyrate). The nitroprusside pad mainly detects acetoacetate. Ketonuria appears in fasting, vomiting, uncontrolled diabetes, and some diets. A “negative ketones” strip does not rule out β-hydroxybutyrate-predominant ketoacidosis.

C&S is culture and susceptibility: grow organisms and test antibiotics. A nitrite or leukocyte pad is a screen, not a colony count and not a susceptibility report.

Sediment: what belongs, what does not

Sediment is the concentrated button of formed elements after the specimen is mixed, a measured volume is centrifuged, and the supernatant is decanted. Reading one unspun drop is not a complete microscopic unless the SOP’s automated method replaces centrifugation.

Cells in UA sediment include red blood cells (RBCs), white blood cells (WBCs, usually neutrophils), and epithelial cells (squamous, transitional, renal tubular). Report them as the SOP counts (commonly per high-power field).

Casts are cylindrical molds formed in the distal tubules and collecting ducts, classically on a Tamm-Horsfall (uromodulin) protein matrix. Hyaline casts may appear after exercise or dehydration. Cellular casts (RBC, WBC, renal tubular) point to kidney involvement, not just a dirty cup. Waxy and granular casts suggest more chronic or stasis-related renal disease. Casts are not crystals, not mucus threads, and not clothing fibers.

Crystals are precipitated salts. Which ones you see depends on pH, concentration, and temperature. Acid urine: uric acid, calcium oxalate, amorphous urates. Alkaline urine: triple phosphate (coffin-lid), amorphous phosphates, ammonium biurate. Many crystals are incidental; some (cystine, large numbers of uric acid in the right context, certain drug crystals) matter. Refrigeration creates extra crystals—do not invent a stone disease from a cold cup.

Bacteria may appear as rods or cocci. In an unpreserved delayed specimen they multiply and lie. Seeing bacteria is not a C&S report.

Yeast (often Candida) shows budding and sometimes pseudohyphae. Distinguish yeast from RBCs: RBCs lyse in acetic acid; yeast does not; yeast buds.

Trichomonas is a pear-shaped flagellate parasite. Motility in a fresh wet preparation is the classic clue. It is a pathogen, not a “contaminant darting around.” Delayed urine kills motility and can cause a false-negative microscopic.

Spermatozoa may appear after intercourse or in some male specimens. Report per SOP; they are not infection and not an artifact.

Mucus appears as threads. It is common and usually not pathologic. Do not upgrade mucus to hyaline casts.

A skin contaminant is material that never came from the urinary tract: squamous epithelial cells from skin or vagina, fibers from clothing or diapers, powder, fecal material. Heavy squamous cells mean poor collection, not pyelonephritis.

An artifact is non-anatomic debris: air bubbles, oil droplets, glass, starch, hair, pollen, fibers. Starch can show a Maltese-cross under polarized light and fool someone looking for cholesterol. If it does not match a cell, cast, crystal, or organism, do not name it as one.

In practice

A first-morning clean-catch arrives for “UA with micro and C&S.” Macroscopic: amber and slightly hazy. Chemical analyses: leukocyte esterase positive, nitrite negative, blood small, protein trace. Microscopic: 10–20 WBCs/HPF, few bacteria, many squamous epithelial cells, a hyaline cast, calcium oxalate, and a clothing fiber. You do not report the fiber as a cast, you do not call squamous cells pyelonephritis, you do not convert the dipstick into a culture, and you send the sterile aliquot for C&S as ordered.

Exam traps

• Random = midstream = clean-catch.
• Casts = crystals = mucus = fibers.
• Dipstick nitrite = C&S.
• Blood pad = only intact hematuria.
• Yeast = RBCs; delayed urine still shows motile trichomonas.
• Heavy squamous cells = kidney infection.

Define the word, name what it is not, and keep C&S off the strip.