Further Outpatient Care
Patients must be under the regular care of a biochemical geneticist and an experienced nutritionist.
Because of the low-phenylalanine, low-tyrosine diet, frequent quantitation of plasma amino acid levels is required. Adjustment is based on these results and on parameters of physical growth.
Further Inpatient Care
Intercurrent illness in tyrosinemia may precipitate subsequent crises based on diminished intake, causing muscle protein catabolism with release of phenylalanine and tyrosine for energy.
Such crises require admission for treatment.
Inpatient & Outpatient Medications
In addition to dietary treatment, the standard of care now requires use of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC), which prevents the formation of fumarylacetoacetate from tyrosine. [23]
Close monitoring of patients taking NTBC is essential, according to protocol requirements.
Subsequent, long-term experience with NTBC (nitisinone) has shown this agent to be very effective in both the acute phase of the disease, as well as in prevention of hepatic cellular carcinoma. In addition, children with initial renal tubular dysfunction show complete remission after long-term treatment with NTBC. [24, 25]
Transfer
Immediately transfer any patient suspected of having tyrosinemia I to a major academic medical center, clinical status permitting.
Deterrence/Prevention
Aside from treatment with NTBC, no other deterrents of disease onset are known.
Complications
Potential complications include the following:
-
Hepatic cirrhosis
-
Renal Fanconi syndrome, including renal tubular acidosis type II
-
Rickets secondary to renal tubular acidosis (RTA)
-
Peripheral neuropathy
-
Abdominal crisis
-
Seizures
-
Hepatoma or hepatocellular carcinoma
Prognosis
Without treatment, patients die from chronic hepatic failure by age 2 years. In the later-onset type, death from hepatic failure or hepatic tumor may occur in mid childhood.
Early liver transplantation poses the usual risks and complications of any major organ transplantation, including the risk of rejection.
Experience with NTBC has become more extensive; the drug appears to be effective in preventing progressive liver and renal disease and in aborting the fulminant clinical onset if started prior to age 1 month, a key reason for advocacy of adding this disorder to newborn screening panels in many places. The long-term results of NTBC therapy are emerging, and while early treatment appears very effective in eliminating cirrhosis and/or hepatomas, development in many affected children has been reported to be slower than normal. [26]
Patient Education
Teach family members how to help the patient adhere to dietary restrictions and medication schedules.
Emphasize the importance of regular follow-up care with a biochemical geneticist.
Family members should understand that hepatic malignancy might develop despite all therapy. Medical follow-up care is imperative.
Prenatal diagnosis is possible for future pregnancies.
-
Tyrosine
