Where are the lemons?

The urine is orange!

The causes of orange urine include:

• Medications:
  Idarubicin — an anthracycline used for hematological malignancies
  Ferrioxamine — an iron chelator that classically causes ‘vin rose’ urine – tends to be orange to reddish-brown
  Oxamniquine — antischistosomal quinoline selective for S. mansoni
  Phenazopyridine — an azo dye used for analgesia in urinary tract infections – it can cause false-positive urine dipstick results for bilirubin and urobilinogen – can have nasty side-effects
  Rifampicin — see below
  Sulfasalazine — 5-aminosalicylate with a local effect on the bowel wall used in inflammatory bowel disease
  Warfarin — urine may be pink or orange
• Foods, supplements, and vitamins:
  Carotenes — e.g. vitamin A, orange juice, pumpkin, and carrots
  B-complex vitamins
  Food dyes — what goes in must come out…
  Senna
  Rhubarb
  Beets and blackberries — urine tends to be red-coloured
• Disorders that cause hypercarotenemia:
  diabetes mellitus
  dietary excess of carotenoids
  hyperlipidemia
  hypothyroidism
  porphyria

Note:

• Urine may also appear ‘orange-ish’ as a result of dehydration or jaundice (hyperbilirubinemia).
• Hypercarotenemia is associated with yellowish skin without scleral icterus (in contrast to jaundice). It can also cause orange discolouration of cerebrospinal fluid (CSF).

Rifampicin

This patient had a cerebral abscess and was being being treated with rifampicin. The orange colour is benign. Other body secretions such as sweat and tears – as well as CSF – may also be discoloured.

Rifampicin is an RNA polymerase inhibitor that is active against most Mycobacteria, most Gram-positive bacteria and some Gram-negative bacteria, eg N. meningitidis, H. influenzae. It is generally reserved for MRSA, mycobacterial infections and prophylaxis of meningitis and epiglottitis. Resistance to rifampicin can occur rapidly if it is used as the sole agent for antibotic therapy.

Adverse effects of rifampicin include gastrointestinal disturbance and elevated liver enzymes. Rarely it may result in Clostridium difficile-associated disease, allergy or hepatitis.

Rifampicin decreases the concentration and reduces the activity of many other drugs. This occurs because rifampicin induces hepatic and intestinal CYP enzymes as well as transporter proteins (e.g. P-glycoprotein). Induction of enzymes and transporter proteins is maximal at about 1 week of therapy and lasts for about 2 weeks after discontinuation.