In spite of these results, however, this combination has been very rarely used to treat prostate cancer in the United States.The antigonadotropic as well as anticorticotropic effects of MGA may be involved in its effectiveness in the treatment of postmenopausal breast cancer via substantially decreasing gonadal and adrenal production of sex steroids and by extension circulating levels of estrogens, by about 80%. Androgenic and antiandrogenic activity
MGA is a weak partial agonist of the androgen receptor (AR). It has been reported to bind to this receptor with 5% of the affinity of the anabolic steroid metribolone. Despite its weak intrinsic activity at the AR, at clinical doses in humans, MGA appears to behave, for all intents and purposes, purely as an antiandrogen. This is based on the fact that no virilizing side effects have been observed with the use of MGA in patients of either sex at dosages up to as high as 1,600 mg per day, the highest that has been assessed. Furthermore, MGA produces detectable androgenic effects in animals only at a dose that is the equivalent of approximately 200 times that typically used for the treatment of prostate cancer in men. However, the medication does have moderate androgenic effects on serum lipids in humans, causing a significant reduction of HDL and LDL cholesterol levels and no change in triglyceride levels at a dosage of only 5 mg/day. Conversely, MGA does not decrease SHBG levels.
Diagnosis
The diagnosis is based on the biochemical findings (increased concentrations of lysine, arginine and ornithine in urine and low concentrations of these amino acids in plasma, elevation of urinary orotic acid excretion after protein-rich meals, and inappropriately high concentrations of serum ferritin and lactate dehydrogenase isoenzymes) and the screening of known mutations of the causative gene from a DNA sample. Treatment
Treatment of LPI consists of protein-restricted diet and supplementation with oral *GeneReview/NIH/UW entry on Lysinuric Protein Intolerance citrulline. Citrulline is a neutral amino acid that improves the function of the urea cycle and allows sufficient protein intake without hyperammonemia. Prognosis
Under proper dietary control and supplementation, the majority of the LPI patients are able to have a nearly normal life. However, severe complications including pulmonary alveolar proteinosis and chronic kidney disease may develop even with proper treatment.Fertility appears to be normal in women, but mothers with LPI have an increased risk for complications during pregnancy and delivery. References
External links
GeneReview/NIH/UW entry on Lysinuric Protein Intolerance