People who have received human growth hormone (HGH) may be at risk of developing the progressive brain disease CJD decades after treatment, say scientists.

HGH has been used by doctors to help stunted children grow normally since 1959.

It was originally collected from human pituitary glands.

We don't know how many more human growth hormone patients might contract CJD

Department of Health

But concerns about the transmission of CJD mean that all supplies of HGH are now manufactured using artificial techniques.

However, Dutch researchers have uncovered evidence that people who received treatment long before the switch to artificial supplies may still be at risk - even if they only received low dose treatment.

They have reported the case of a man who developed CJD 38 years after receiving human derived growth hormone.

Basic test

The 47-year-old man was given only a low dose as part of a diagnostic procedure, rather than being given full treatment, which may explain why the incubation period lasted so long.

He had delayed growth as a child, for which he underwent testing using a form of human derived growth hormone to exclude growth hormone deficiency when he was just nine.

The source of the hormone used is not known, but it is highly unlikely that this man would have developed CJD by chance, say the authors.

His symptoms began with numbness in both arms, which progressed to difficulty in walking and involuntary movements.

After eight months he was admitted to hospital and died five months later. CJD was confirmed at post mortem examination.

The first Dutch patient with CJD associated with human growth hormone died in 1990, but she had been treated with deep muscle injections over several years on various occasions.

There are 564 other registered recipients of the hormone in the Netherlands, who were treated before 1985, who are currently not suspected of having CJD.

But the authors conclude: "This case indicates that still more patients with iatrogenic CJD can be expected in the coming years.

"Another implication of our study is that CJD can develop even after a low dose of human growth hormone."

An iatrogenic disease is one caused by medical treatment.

UK record

A spokesman for the Department of Health said treatment with natural human growth hormone was ended in May 1985 in the UK following the death of a US patient from CJD.

By March 2000, 34 out of the total of 1,900 people who had received the natural form of the hormone had died of CJD in the UK.

Some 170 had died of other causes, of which about half had died of cancer of the pituitary gland which caused their original growth problems.

He told BBC News Online: "We don't know how many more human growth hormone patients might contract CJD as we haven't identified the causative agent, and cannot test for it.

"If low doses presented a risk I would have thought that other cases would have come to light before now."

The paper is published in the Journal of Neurology Neurosurgery and Psychiatry.