A technique for measuring total body calcium (TBCa) by in vivo
neutron activation analysis (IVNAA) was described. It had a
precision of 1.8% for a dose of 13 mSv. TBCa was measured in 40
healthy volunteers and the mean value (SD) for 20 men was 1143g
(134g) and for 20 wcmen it was 821 g (124g).
A formula for predicting TBCa (TBCap) from height in men and
from span and years postmenopause in wcmen was derived. The results
from patient groups were expressed as a ratio of TBCa to TBCap, the
calcium ratio (CaR).
The mean CaR in eight wcmen with wrist fracture was 1.00
(0.10, SD) and in 14 wcmen with vertebral fractures was 0.87 (0.06,
SD). The latter group had a significantly lower CaR than the female
controls of 1 .00 (0.07, SD, P<0.001). The TBCa was normalized for
span alone to obtain an index reflecting the bone lost since the
menopause, the osteopaenia index. Patients with vertebral fractures
all had values below 0.78 and so this was considered the fracture
threshold.
A low mean value for CaR was found in 14 patients with primary
hyperparathyroidism. Significant increases in TBCa were found in
four out of seven patients followed for up to 34 months
postoperatively. The initial mean CaR was 0.85 (P<0.001 ).
Seven wcmen with osteomalacia due to malabsorption had a low
mean TBCa and osteopaenia index (P<0.001). One patient who was
remeasured after eight months of vitamin D therapy had an 18%
increase in TBCa, the largest increase found in any patient in the
present study.
Twelve patients were measured prior to, or shortly after,
renal transplantation. The eight men had a mean CaR of 0.93
(P<0.05) and the four wcmen a mean value of 0.82. There was no
significant change following renal transplantation over an average
of 17 months. This result was attributed to a balance between the
healing of renal osteodystrophy and the osteopaenic effect of
steroid therapy.
Forty-one men studied after peptic ulcer surgery had a low
mean CaR of 0.94 (0.07, SD, P<0.01 ). The reduction in bone mass was
similar for patients after partial gastrectomy and for those after
vagotomy and drainage procedures. The hypothesis was proposed that
bone disease after peptic ulcer surgery was due to secondary
hyperparathyroidism caused by calcium malabsorption and not by
subclinical osteomalacia. This was supported by the following
findings. Plasma 25-hydroxycalciferol was normal when compared
with season-matched controls. However, there were low plasma
calcium and high parathyroid hormone levels compared with
age-matched controls. Dietary calcium was normal but 7-day calcium
retention was increased when the calcium was given as a solution
