Bone mineral density after allogeneic bone marrow ... - Nature

Bone Marrow Transplantation, (1999) 24, 885–889  1999 Stockton Press All rights reserved 0268–3369/99 $15.00 http://www.stockton-press.co.uk/bmt

Bone mineral density after allogeneic bone marrow transplantation M Kauppila1, K Irjala2, P Koskinen2, K Pulkki2, P Sonninen3, J Viikari1 and K Remes1 Departments of 1Medicine, 2Central Laboratory and 3Radiology, Turku University Central Hospital, Turku, Finland

Summary: Bone turnover markers and bone mineral density (BMD) were studied in 25 adult patients (14 females, 11 males) who had undergone allogeneic bone marrow transplantation (BMT). The interval from BMT to the first examination was at least 1 year (mean 3, range 1– 10). Mean age of the patients at the time of first evaluation was 42 (range 19–54) years. Blood samples and urine collections for evaluation of biochemical factors reflecting skeletal turnover were performed together with the first BMD measurement. BMD was measured from the lumbar vertebrae (L2 to L4) with computed tomography and results were expressed as Z-scores. At the time of the first measurement five patients (20%) had Z-scores ⬍−2.5 s.d. and 12 patients (48%) between −1 and −2.5 s.d. In 12 patients BMD assessments were repeated and it seemed that reduction in BMD had mostly occurred during and shortly after BMT and remained the same during follow-up. The cross-linked carboxyterminal telopeptide of type I collagen (ICTP) correlated negatively with BMD (r = −0.45, P = 0.045) as did bone-specific alkaline phosphatase (BAP; r = −0.64, P = 0.002). No correlation between BMD and time interval from diagnosis to BMT, conditioning regimen, corticosteroid use or hospital stay during transplantation was found. In conclusion, bone disease is common after BMT. Our findings demonstrate an increased collagen and bone turnover and a high risk of osteoporosis. BMD measurements must be repeated regularly and collagen markers such as ICTP and BAP can be beneficial in estimating the activity of bone disease. Keywords: allogeneic bone marrow transplantation; ICTP; bone-specific alkaline phosphatase; bone mineral density; osteoporosis

Transplant recipients are at risk of osteoporosis. Muchmore et al1 reported low mean density of vertebral bone in heart transplant patients. Bone loss takes place mostly during the initial year after transplantation.2 Rapid loss of vertebral mineral density has also been reported after renal transplantation, with most of the loss occurring within the first 6 months.3 In the study by McDonald et al4 spinal bone mineral density (BMD) decreased by 24% in the first 3 months after liver transplantation with no further decrease thereCorrespondence: M Kauppila, Turku University Central Hospital, Department of Medicine, Kiinamyllynkatu 4–8, 20520 Turku, Finland Received 12 October 1998; accepted 20 May 1999

after. Bone loss was related to number of hospital days but not to any other factor. Patients after allogeneic BMT are also exposed to numerous factors that can affect bone mineral metabolism: induction and consolidation therapies, bed rest,5,6 conditioning regimen for BMT, steroids,7 CsA therapy8,9 and GVHD.10 In female patients disturbance of gonadal function causes chronic estrogen deficiency11 with an increased risk for osteoporosis. Carlson et al12 studied the effect of myeloablative therapy on bone metabolism during the first 3 months after transplantation and found significant changes in serum markers of bone metabolism, which implied a net loss of bone over the study period. In 1997 Keilholz et al13 reported normal BMDs after ABMT with a median interval of 5 years from autografting. The purpose of the present study was to evaluate the occurrence of bone disease after BMT by measuring BMD and biochemical markers of bone metabolism. Patients and methods We examined 25 (14 females, 11 males) adult patients after BMT so that the interval from transplantation to the first examination was at least 1 year (mean 3, range 1–10). The mean patient age at the time of first evaluation was 42 (range 19–54) years. Blood samples and urine collections for evaluation of biochemical factors associated with skeletal turnover were performed at the time of the first BMD measurement. BMD assessment was repeated in 12 (six females, six males) patients at least once. Twelve of 14 females had estrogen + progesterone replacement therapy and one male received testosterone injections. Two of the females had continuous clodronate after BMT and in one male patient it was started during the follow-up period. Patient characteristics are shown in Table 1. Bone mineral density BMD was measured with computed tomography (CT; Somatom CR, Siemens, Erlangen, Germany) with a European bone mineral reference standard.14 After a lateral lumbosacral scout image, single 8 mm thick slices were taken through the middle of the lumbar vertebrae L2–L4. A region of interest (ROI) was manually selected in the trabecular part of the each vertebra for measuring BMD. Conversion of density in the region of interest to g/m3 was made by using a densitometric phantom in the images. Precision of Somatom CR has been shown to be 1.5 %.15 The results of BMD are expressed as T- or Z-scores. Reference values are derived from European control material.14 This

Bone mineral density after allogeneic BMT M Kauppila et al

886

Table 1

Patient characteristics Female (n = 14)

Male (n = 11)

Total (n = 25)

40 26–50

36 16–50

38 16–50

Diagnosis AML ALL CML NHL Burkitt/LL MM SAA

2 1 5 1 0 3 2

5 0 2 0 3 1 0

7 1 7 1 3 4 2

Conditioning regimen TBI/CY TNI/CY BU/CY

7 2 5

8 0 3

15 2 8

6 2 4 0

0 0 0 1

6 2 4 1

2

1

3

Age at the time of BMT (years) Mean Range

Hormone replacement therapy E2 patcha E2 patch + P pillsb E2 pills + P pills Testosteronec Bisphosphonate therapy Clodronate

AML = acute myelogenous leukemia; ALL = acute lymphoblastic leukemia; CML = chronic myelogenous leukemia; NHL = non-Hodgkin’s lymphoma; Burkitt = Burkitt’s lymphoma; LL = lymphoblastic lymphoma; MM = multiple myeloma; SAA = severe aplastic anemia; TBI = total body irradiation; CY = cyclophosphamide; TNI = total nodal irradiation; BU = busulphan. Conditioning regimens for transplantation were TBI + CY = 12 Gy in five fractions on 5 consecutive days (10 Gy to the lungs), CY 60 mg/kg on 2 consecutive days. TNI + CY = 8 Gy in five fractions on 5 consecutive days, CY 60 mg/kg on 2 consecutive days. BU + CY = busulphan 4 mg/kg on 4 consecutive days, CY 60 mg/kg on 2 consecutive days. a E2, estradiol; bP, progesterone; cTestosterone; testosterone enanthate 250 mg i.m. every 3 weeks.

linear Z-score describes the deviation from mean values from gender- and age-matched controls without evidence of bone disease. The low bone mass is T-score within −1 s.d. and −2.5 s.d., and BMD below −2.5 s.d., by definition, represents osteoporosis.16,17 Laboratory measurements Blood samples were taken after an overnight fast and rest at 8.00 am. Plasma ionised calcium, serum phosphorus, parathyroid hormone, alkaline phosphatase and bonespecific alkaline phosphatase (BAP) were measured. The cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and the aminoterminal propeptide of type I procollagen (PINP) were measured as serum markers of collagen metabolism. Plasma interleukin-6 (IL-6) was also determined. Twenty-four hour urine specimens were collected for measurement of daily excretion of creatinine, calcium, hydroxyproline, phosphorus and magnesium and are also expressed as a ratio to urinary creatinine excretion. Reference ranges for the study parameters are shown in Table 2. Serum parathyroid hormone was measured with the Ntact PTH IRMA kit (Incstar, Stillwater, MN, USA). Alka-

line phosphatase was measured at 37°, with a Hitachi 704 automatic analyzer (Hitachi, Kioto, Japan). Bone-specific alkaline phosphatase was analyzed by ELISA (AlkphaseB; Metra Biosystems, Mountain View, CA, USA). ICTP and PINP were measured by RIA (Orion Diagnostica; Espoo, Finland). The plasma levels of IL-6 were measured with sandwich-type ELISA (Quantikine; R&D Systems, Minneapolis, MN, USA). Urine hydroxyproline was measured with high pressure liquid chromatography. Statistical analysis Pearson’s correlation coefficients were calculated in correlation analyses of BMD with time from diagnosis to transplantation, the hospital stay during transplantation, dose of methotrexate (MTX), dose of corticosteroid, BAP, ICTP, PINP and IL-6. Student’s unpaired t-test was used to evaluate differences in BMD between the two conditioning regimens. Results BMD measurements at the time of first examination demonstrated that five patients (20%) had very low densities, ie their BMDs (Z-score) were below −2.5 s.d. (three females, two males). BMDs of 12 patients (48%) were in the range from −1 to −2.5 s.d. and only in eight patients (32%) was BMD normal (Figure 1). Twelve of the patients were repeatedly measured at least once and it seemed that if the BMD was abnormal it had changed mostly during and shortly after BMT and remained the same during follow-up (Figure 2). One female had severe gastrointestinal grade IV GVHD and needed i.v. nutrition for 2 years. During her recovery her BMD also improved (Z-score from −4 s.d. to −3.1 s.d. and further to −2.2 s.d.; Figure 2). Blood and urine measurements reflecting bone metabolism are shown in Table 2. There was an inverse correlation with BMD and serum ICTP; ICTP was higher in patients with low Z-scores (⬍ −2.5 s.d.; r = −0.45, P = 0.045) as was also serum BAP (r = −0.64, P = 0.002; Figure 3). On the contrary, there was no correlation between BMD and plasma IL-6 or serum PINP. There were also no correlations between BMD and time from diagnosis to transplantation, conditioning regimen or hospital stay during transplantation, nor was there any correlation between BMD and MTX or corticosteroid use. Discussion We found that low BMD is a common finding after BMT. In our patients, the BMD of 17 patients (68%) was significantly decreased. In one study BMD did not change after intensive therapy but the patients had undergone autologous transplantation after which the risks for osteoporosis are obviously much less than after allogeneic BMT.13 In the recent cross-sectional study by Bhatia et al18 BMD was decreased in children but not in adults. This finding disagrees with our results but can possibly be explained by a smaller number of adult patients (n = 13, of whom 11


Table 2

887

The mean values of markers of bone metabolism Male

Female

Mean

Range

1.29 0.9 38 259 25 4.5

1.18–1.39 0.7–1.3 17–69 79–736 8–48 2.3–9.1

Serum PINP (␮g/l)

76

22–276

Plasma IL-6 (ng/l)

2.7

⬍0.7–6.1

Daily urine excretion Creatinine (mmol) Calcium (mmol) Calcium/Creatinine Hydroxyproline (␮mol/m2) Hydroxyproline/Creatinine Phosphorus (mmol) Phosphorus/Creatinine Magnesium (mmol) Magnesium/Creatinine

15 3.2 0.2 138 9.2 35 2.3 4.8 0.3

10–23 1.5–8.1

Plasma ionized Ca++ (mmol/l) Serum phosphorus (mmol/l) Serum parathyroid hormone (ng/l) Serum alkaline phosphatase (U/l) Serum bone-specific alkaline phosphatase (U/l) Serum ICTP (␮g/l)

Bone mineral density, Z-score (s.d)

0.5 0

–1

–2 –2.5 –3

–4

–5 Females (n = 14)

males (n = 11)

Figure 1 BMDs at the time of first measurement with the mean of 3 (range 1–10) years after BMT. Results of computed tomography examination of lumbar vertebrae (L2–L4) are expressed as Z-scores. Zscores −1 and −2.5 are indicated.

received allogeneic BMT) and by the fact that this patient material consisted mainly of patients with CML where usually only light chemotherapy has preceded BMT. BAP is a marker of bone turnover.19 In renal transplant patients it has risen following transplantation and is considered as a marker of osteoblast activation.20 It has been reported that it can even correlate with BMD in post-menopausal females.21 The earlier study by Withold et al22 of biochemical markers reflecting bone turnover is in agreement with our observations after BMT where BAP and BMD had an inverse correlation with BMD (Figure 3). Type I collagen is the predominant protein (90%) in bone. During formation of new collagen relatively large parts of the molecule split off from both ends and are

52–318 21–47 2.7–7.6

Mean

Reference range Range

1.28 1.2 47 217 19

1.17–1.38 0.8–1.8 22–117 75–618 8–35

4.7

3.2–8.1

52 2.8

10–121 ⬍0.7–6.7

1.18–1.32 0.7–1.3 10–55 60–270 10–23 1.3–5.2 1.5–5.0 20–76 19–84 ⬍3.2

9 2.8 0.3 88 9.8 23 2.5 3.0 0.3

7–11 0.3–9.8

8–15 1.3–6.5

32–166

60–180

16–34

20–50

1.1–6.5

0.6–12.0

released into the extracellular fluid. Thus, the carboxyterminal propeptide of type I procollagen (PICP) and aminoterminal propeptide of type I procollagen (PINP) correlate with bone formation. Resorption of old bone cleaves collagen into smaller fragments. One of these fragments is the crosslinked carboxyterminal telopepetide of type I collagen (ICTP) which can be used as resorption marker of bone.23 We found an inverse correlation between BMD and ICTP level (Figure 3), whereas serum PINP, a marker of synthesis, tended to remain normal. Many cytokines affect bone metabolism, including IL-1, IL-6, TNF and GM-CSF. IL-6 can stimulate bone resorption, at least in vivo.24 IL-6 can be produced by osteoblasts, production of which can be modulated by parathyroid hormone.25 Plasma IL-6 levels were mostly normal in our patients but tended to have a correlation with decreased BMD (P = 0.07). Hypogonadism is a well-known predictor for osteoporosis. In females older than 40 years, irreversible ovarian failure is the almost universal result of 0.4–0.7 Gy of conventionally fractionated radiation to both ovaries. In our patients there was no correlation between BMD and conditioning regimen whether or not it included TBI; all but one of our patients were menopausal. In spite of hormone replacement therapy, most of them (13/14; 93%) had high serum LH and FSH levels indicating that the hypothalamus–pituitary axis was not suppressed.26 Most often the estrogen dose used is titrated in consideration of clinical symptoms and usually this dose is thought to be high enough to prevent osteoporosis. Osteoporosis in males is a heterogeneous condition and it should always raise the possibility of hypogonadism. Hypogonadal osteoporosis is associated with a high turnover state, which reverses towards normal following androgen replacement therapy. The most significant increase in


888

10

8

0 –1

ICTP ( µ g/l)

Bone mineral density, Z-score (s.d.)

a

–2.5

6

4

r = –0.45 P = 0.045

Females

2

–5 0

1

2

3

4

5

6

7

8

9

10

11

0

Time (years from BMT)

–5

–4

–3 –2.5

–2

–1

0

0.5

0

0.5

b 0

50

–1

40 –2.5

BAP (U/l)



Males –5 0 1 2 3 4 5 6 7 8 9 10

30

20

r = –0.64 P = 0.002

20

Time (years from BMT) Figure 2 BMDs during follow-up in 12 patients after BMT. Computed tomography examinations are from lumbar vertebrae (L2–L4) and are expressed as Z-scores. The patient indicated with ✴ had initially severe gastrointestinal GVHD and i.v. nutrition. During the recovery bone density improved.

BMD is seen during the first year of testosterone treatment.27 No normal FSH values were discovered, but in 7/11 (64%) of our patients LH was within normal limits. In the material reported here only one male used testosterone therapy and he had also a very low BMD (Z-score: −2.5 s.d.). Physical inactivity or prolonged bed rest results in loss of bone mass.5,28 The recovery from immobilization bone loss has also been observed.6 The time from the diagnosis of hematologic disease to recovery after BMT is several months and most patients spend more time at the hospital than at home during this period. We found, however, no correlation between BMD and the time from diagnosis to BMT or the length of hospital stay. Patients who require continuous treatment with glucocorticoids are known to be at risk for the development of osteoporosis. Steroids are commonly used if GVHD needs therapeutic intervention. Excess bone is lost during treatment of chronic GVHD.10 After cessation of steroid treatment, some recovery from osteoporosis may occur.29 Seven of our patients had corticosteroid treatment at the time of first BMD measurement and four of them had low BMD

10

0 –5

–4

–3 –2.5

–2

–1

Bone mineral density, Z-score (s.d.) Figure 3 Correlation between BMD and ICTP (a) and BAP (b) at the time of the first computed tomography examination in 20 patients after BMT.

(Z-scores: −2.5, −3, −3, −4 s.d.). In addition to glucocorticoids, CsA is the main drug for prophylaxis and treatment of GVHD. CsA therapy has been associated with decreased serum testosterone levels30 and accelerated bone turnover.22 One of our subjects had severe intestinal GVHD lasting for two years. As the result of malabsorption and long-term treatment with glucocorticoid and CsA she had the lowest BMD which improved (Z-score from −4 to −2.2 s.d.) during her recovery. In summary, low BMDs are common after BMT. Five of our patients (20%) had a very low BMD at a young age, and many more (48%) were at increased risk for osteoporosis. The two most important risk factors for long-term skeletal health are known to be low peak bone mass and subsequent increased rate of bone loss. When transplanted at an early age (⬍35 years) the patient has possibly never reached the maximum bone density which may aggravate


BMD decrease. Bone loss seems to occur around the transplantation period and afterwards bone density remains about the same. In some patients BMD may improve after GVHD has resolved. BMD measurements must be repeated regularly and serum biochemical markers such as BAP or ICTP can be beneficial in estimating bone disease.

15

Acknowledgements

17

The Turku University Foundation, The Cancer Society of SouthWestern Finland and The Medical Research Foundation of Turku University Central Hospital have supported this study.

18

16

19

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