Bone histomorphometry in celiac disease

Bone metabolism in celiac patients is not well understood and there are no previous histomorphometric studies on bone of patients with celiac disease. The aim of the study was to investigate bone metabolism in celiac patients using bone histomorphometry, measurement of bone mineral density (BMD) and biochemical parameters.

The patient groups included 19 men and 23 women with previously diagnosed celiac disease in remission (group I), 7 women not in remission (group II) and 19 women and 9 men with newly diagnosed celiac disease (group III). Static and dynamic parameters of bone structure, formation and resorption were measured using undecalcified sections. The following parameters were obtained: bone volume (BV/TV; %), osteoid volume (OV/BV; %), osteoid surface (OS/BS; %), resoprtion surface (ES/BS; %), osteoid thickness(Oth; microm), mineral apposition rate (MAR; microm/day), and mineralization lag time (MinLag; day). BMD was measured at the spine (L2-4) and left femoral neck, trochanter and Ward's triangle. Serum calcium (S-Ca; mmol/L), alkaline phosphatase (AP; U/L), intact parathyroid hormone (S-PTH; ng/L), 25-hydroxyvitamin D (S-25(OH)D; nmol/L), cross-linked carboxyterminal telopeptide of human type I collagen (S-ICTP; microg/L) and C-terminal extension peptide of type I procollagen (S-PICP; microg/L) were analysed.

In the histomorphometric analysis there were no significant differences in static or dynamic parameters between the groups. Very low bone mass (< 10%) was found in one patient in every group. OV/BV was increased (> 3.5%) in all groups (31% in group I, 13% in group II and 29% in group III). OS/BS was increased (> 36.5%) in groups I and III (17% and 29% respectively). In group II OS/BS was normal in all patients. Mineralization defect was found in four patients in group I and in two patients in group III with otherwise normal histomorphometric results. ES/BS was increased in three patients in group I and III and in one patient in group II. One female patient in group III had increased osteoid parameters, resorption surface, S-PTH and low concentration of vitamin D reflecting hyperparathyroid changes in bone. S-PTH was increased (66-87 ng/L) in four patients in group III and one of these patients had hyperparathyroid histological changes in bone.

Static and dynamic histomorphometry of iliac crest bone biopsy are useful tools to evaluate bone metabolism in celiac disease especially if hyperparathyroidism or mineralization defect are suspected. Hyperparathyroidism may be a problem in the patients before introducing gluten-free diet. Mineralization defect and osteomalacic changes are common later on irrespective of whether the patients are in remission or not.