Medicines shortages causes

European Medicines Agency (EMA) (2012) Reflection paper on medicinal product supply shortages caused by manufacturing/good manufacturing practice compliance problems, 22.11.2012. http // www.ema.europa.eu/docs/en GB/document library/Other/2012/ ll/WC500135113.pdf. Retrieved 14 Apr 2013... 

It all works much better if we consider some simpler cases that are less obvious in ordinary life but still have greater importance for medicine than skin or eye color. Take, for example, the disease phenylketonuria, which 1 mentioned briefly in Chapter 8. If left untreated it produces severe mental retardation and, in many cases, death before the age of 25. It is caused by an incapacity to convert the aminoacid phenylalanine into another aminoacid, tyrosine. It is not, however, a deficiency disease, because its harmful effects are not caused by a shortage of tyrosine, and cannot be avoided by adding tyrosine to the diet. Instead they are caused by the toxic effects on the brain of a substance called phenylpyruvate, which the body produces in its efforts to remove the excess of phenylalanine. The name of the disease reflects the fact that phenylpyravate, which belongs to a general class of chemical substances known as phenylketones, is excreted in the urine of affected people. This provides a simple method of diagnosis, and the disease is treated by carefully controlling the diet so that it provides no more phenylalanine than is needed for normal health. There is then no surplus to be converted into phenylpyruvate. 

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