Ochronosis: alkaptonuria (“black urine disease”) due to excretion of homogentisic acid (black color may only appear after urine stands for a period of time, allowing oxidation of homogentisic acid)
Myoglobin is a Low Molecular Weight (17 kDa) Heme Pigment, Which Does not Bind to Haptoglobin: therefore, it is not present to any significant extent in the plasma
Porphyrinuria
Red-Brown Urine (May Be “Coca Cola”-Colored)
Beet Ingestion
Hemoglobinuria (Urine Hemoglobin)/Hemosiderinuria (Urine Hemosiderin) (see Hemoglobinuria, [[Hemoglobinuria]] and Hemosiderinuria, [[Hemosiderinuria]])
Myoglobin is a Low Molecular Weight (17kDa) Heme Pigment, Which Does not Bind to Haptoglobin: therefore, it is not present to any significant extent in the plasma
Orange Urine
Phenazopyridine (Pyridium)* (see Phenazopyridine, [[Phenazopyridine]]): with associated orange secretions
Rifampin (see Rifampin, [[Rifampin]]): with associated orange secretions
Technique: utilizes the characteristic of heme to act as a pseudoperoxidase -> when heme-containing urine is exposed to a peroxide and chromogen, a color change occurs
Sensitivity: urine dipstick for occult is highly sensitive and can detect 1-2 red blood cells per high-powered field
Presence of Ascorbic Acid (Vitamin C) May Result in a False-Negative Test (see Vitamin C, [[Vitamin C]]): vitamin C interferes with the peroxidase reaction
Some dipsticks are able to oxidize vitamin C to mitigate this issue
