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PAPERS: Ewa Lundgren, Eva Szabo, Sverker Ljunghall, Reinhold Bergström, Lars Holmberg, and Jonas Rastad Population based case-control study of sick leave in postmenopausal women before diagnosis of hyperparathyroidism BMJ 1998; 317: 848-851 [Abstract] [Full text]

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Conclusion on sick leave was an overstatement

David Taylor   (23 October 1998)

Diagnosing Primary Hyperparathyroidism

John Hinnie   (23 January 1999)

Conclusion on sick leave was an overstatement 23 October 1998
David Taylor Send response to journal: Re: Conclusion on sick leave was an overstatement	Dear Sir The conclusion printed in the BMJ(1) that "a case control analysis of sick leave during the five years before the diagnosis showed that women with hyperparathryroidism were 12 times more likely to take sick leave for at least half the investigated period" was a considerable overstatement. The statement was based on sub group analysis of just 13 of the original 109 women in the trial. This group of 109 had been reduced to 60 by their willingness to submit themselves to surgery. They reasonably justified this by requiring the group to have had a histological diagnosis. Nevertheless, this personal preference is very likely to be a marker for symptoms and illness, hence this group is more likely to have co-morbidity. Secondly this group of 60 (further reduced to 48) is yet again reduced to 13 by choosing those with greater than half time absent from work, an arbitrary figure. The conclusion should have read, 'a sub group of those who took more than half the time off sick, were twelve times more likely to have had hyperparathyroidism than controls'. In reality the 48 cases, of the original 109, were 2.56 (total of 317 against 124 days off sick) times more likely to have taken time off. Yours sincerely Andy Ross and David Taylor 57 Woodland Road Northfield Birmingham B31 2HS BMJ 1998;317:848-51. "Women later diagnosed with hyperparathyroidism take more sick leave"
Diagnosing Primary Hyperparathyroidism 23 January 1999
John Hinnie, Lecturer in medicine Glasgow Royal infirmary, Scotland Send response to journal: Re: Diagnosing Primary Hyperparathyroidism	Editor, I read with interest the recent paper by Lundgren et a1 l demonstrating increased morbidity (as witnessed by an increased incidence of sick leave) in patients with primary hyperparathyroidism (PHP). This confirmed a long held personal clinical impression of my own. I would like to point out a problem with their criteria used for diagnosing primary hyperparathyroidism. This was done by measuring fasting serum calcium and parathyroid hormone levels in women attending population based mammography screening. In about half of the cases found histology on resected glands was used to verify the diagnosis. However, no reference was made to the fact that the cases obtained could include some patients with familial hypocalciuric hypercalcaemia (FHH). This benign form of hypercalcaemia has the biochemical features of mild PHP, i.e. mild hypercalcaemia with inappropriately high parathyroid hormone 2, and can lead to the misdiagnosis of FHH as PHP. Similarly parathyroid histology can reveal hyperplasia in some cases of FHH 3, so that where there is doubt about the diagnosis a return of serum calcium and PTH to normal following removal of the suspect parathyroid gland is the best way of confirming PHP. As far as I am aware no estimate of the prevalence of FHH can be found in the literature, although I accept that it is much less common than PHP. Data from my local population suggest that FHH has a prevalence of at least 1 in 74,000 (unpublished results) in the West of Scotland, while others have shown that PHP may have a prevalence as high as 1 in 1,000 4. It is probable therefore that even if some of the PHP cases of Lundgren et al were in fact FHH, the small numbers concerned would not alter their conclusions. However, it is erroneous to assume that hypercalcaemia with raised parathyroid hormone is diagnostic of PHP. John Hinnie Lecturer in Medicine University Dept. of Medicine Glasgow Royal Infirmary Glasgow G31 2ER REFERENCES 1. Lundgren E, Szabo E, Ljunghall S, Bergstrom R, Holmberg L, Rastad J. Population based case-control study of sick leave in postmenopausal women before diagnosis of hyperparathyroidism. BMJ 1998;317:848-851. (26 September). 2. Marx SJ. Familial hypocalciuric hypercalcaemia. N Eng J Med 1980;303:810-811. 3. Marx SJ, Spiegel AM, Brown EM, et al. Circulating parathyroid hormone activity: familial hypocalciuric hypercalcaemia versus typical primary hyperparathyroidism. J Clin Endocrinol Metab 1978;47:1190-1197. 4. Boonstra CE, Jackson CE. Serum calcium survey for hyperparathyroidism. Am J Clin Pathol 1971;55:523-526.