Tyrosinemia, the odor of rancid butter syndrome, is identified by a distinctive cabbagelike odor This syndrome is caused by a deficiency of fumarylacetoacetase which results in the buildup of succinylacetone, the decarboxylation product of succinyl acetoacetate, a compound derived from the tyrosine catabolic intermediate fumarylacetoacetate Clinical presentation may include failure to thrive, which may precede the appearance of more dramatic findings in tyrosinemia, including vomiting and diarrhea, which rapidly progress to bloody stool, lethargy, and jaundice, irritability, seizures, coma, progressive neurologic deterioration, and can result in early death secondary to infection and liver failure In some cases, restriction of dietary phenylalanine and tyrosine has been helpful Cystinuria is caused by genetic mutations, resulting in inadequate reabsorption of cystine in the proximal of the kidney (SLC3A1 and SLC7A9) This causes an excessive concentration of this amino acid in the urine, which may precipitate out of the urine and form crystals or stones in the kidneys, ureters, or bladder Patients with cystinuria usually present with renal colic, hematuria, chronic backache, and/or urinary tract infection Since cystine is one of the sulfurcontaining amino acids, the urine may have the characteristic odor of rotten eggs The foundation of cystine stone prevention is adequate hydration and urinary alkalinization Toxicologic Considerations Recognition of a characteristic odor is vital for rapid diagnosis and treatment of some potentially lethal ingestions prior to laboratory identification ( Table 50.1 ) (see Chapter 102 Toxicologic Emergencies ) Due to the increased availability of both medical and recreational marijuana, medical care providers need to be attentive to its impact on children Marijuana refers to the dried leaves, flowers, stems, and seeds from the hemp plant Cannabis sativa , which contains the psychoactive chemical delta-9tetrahydrocannabinol (THC), as well as other related compounds This plant material can also be concentrated in a resin called hashish or a sticky black liquid called hash oil Marijuana is usually smoked and has a pungent and distinctive, usually sweet-and-sour, odor that is easily recognized Marijuana is also available as an edible, defined as a food item made with marijuana or infused with marijuana oils Edibles are available in a wide variety of foods such as baked goods, sauces, candies (including animal or fruit-shaped gummies, lollipops, and chocolates), and as a beverage The amount of THC can vary in edible marijuana products, especially in homemade marijuana edibles, making it harder to control how much THC is consumed