European Jourml of Clinical lnuestigarion (1978) 8,425-426

SHORT COMMUNICATION

Humoral hypercalcaemia in a patient wi th renal-cell carcinoma DAVID POWELL, JOSEPH MCPARTLIN & PETR SKRABANEK, Endocrine Unit, Mater Misericordiae Hospital, Dublin, Ireland

Received 30 May 1978 and in revised form 31 August 1978

Abstract. In a patient with hypercalcaemia secondary to a renal-cell carcinoma, a concentration gradient of bio- activity was detected between the tumour effluent vein and the peripheral venous blood that was capable of stimulating adenylate cyclase in bone cells. Immuno- reactive PTH was undetectable in the tumour effluent and in the peripheral blood. It is concluded that a non- parathyroid humoral factor whose action involved cyclic AMP stimulation was responsible for the hypercalcaemia.

Key words. Tumour hypercalcaemia, bone adenylate cyclase, parathyroid hormone, prostaglandins.

Introduction

The occurrence of non-parat hy roid hum oral hyper cal- caemia in patients with extra-skeletal neoplasms was recently described [ l , 21 . Evidence has accumulated that prostaglandins may be the responsible agents in certain instances [ 2 4 ] but an arterio-venous gradient of hypercalcaemic bioactivity across the tumour has not been shown. We report here detection of non-parathyroid bioactivity causing stimulation of bone-cell adenylate cyclase in the plasma and tumour effluent in a patient with a renal cell carcinoma and hypercalcaemia which was corrected by nephrectomy.

Patient, Materials and Methods

A 63-year-old man was admitted to hospital in a drowsy, confused state which had gradually developed over 2 months. Clinical examination revealed cachexia, dehy- dration, and a mass in the left hypochondrium. After rehydration, the following laboratory data were re- corded: serum calcium 3.1 mmolfl, serum phosphate 1.1 mmol/l, Serum magnesium 0.8 mmol/l, alkaline phosphatase 160 IU, creatinine 106 pmol/l, urea 7.2 mmol/l, sodium 135 mmolb, potassium 3.8 mmol/l, and chloride 104 mmol/l. Arterial pH was 7.32, pCOz was 5.1 kPa, and standard bicarbonate was 19 mmolb.

Correspondence: Dr D. Powell, Endocrine Unit, Mater Miseri- cordiae Hospital, Dublin 7 , Ireland.

@ 1978 Blackwell Scientific Publications 0014-2972/78/12004)425 $02.00

Haemoglobin was 10.5 g/dl, with a normochromic, nor- niocytic film. A mid-stream urine specimen contained 1000 red blood cells and 18 white blood cells per mm’, protein 200 mg/l, and was sterile. Skeletal X-rays showed no evidence of metastatic or metabolic bone disease, and chest X-ray was normal. Intravenous pyelography de- monstrated a large mass in the lower third of the left kidney, suggestive of a hypernephroma, and there was no evidence of nephrocalcinosis. Mithramycin therapy was needed to control hypercalcaemia preoperatively. At operation a large left renal tumour was removed. There was no evidence of local spread of tumour. Immediately prior to removal of the tumour, blood was taken simul- taneously from the left renal vein and from a peripheral vein, spun, and the plasma frozen for subsequent assays. Histology of the tumour revealed a clear-cell carcinoma with multiple necrotic areas. Postoperatively, the serum calcium returned to normal within 24 h, and remained normal thereafter, apart from mild hypocalcaemia on the fifth and eighth postoperative days. The patient’s confused state cleared completely, and he made an un- eventful recovery. At follow-up 4 months later, he was symptomatically well, and he had normal serum calcium and a normal chest X-ray.

Parathyroid hormone (PTH) was assayed by radio- immunoassay as described previously [ 1 ] using anti- serum GP-1, which was shown to recognize the biologi- cally active portion of PTH and also proPTH [5]. A bioassay for factors influencing bone metabolism was carried out, using monolayer cultures of bone cells from rat calvaria and studying the increase in intracellular cyclic AMP resulting from added test material. Bone cells obtained by collagenase digestion of calvaria from new-born rats were cultured in monolayers for 7 days. 1 rnl of fresh culture medium and 1 ml of test plasma were added to bone cells for 150 s. The reaction was terminated by discarding the plasma-containing medium and by adding ice-cold saline. The intracellular CAMP was extracted by trichloracetic acid and assayed by a competitive binding method [6] .

Results

The paired renal vein and peripheral vein plasma samples

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426 DAVID POWELL, JOSEPH MCPARTLIN & PETR SKRABANEK

were assayed for PTH. Immunoreactive PTH was not detected in either sample. In the cAMP bioassay, tumour effluent added to bone-cell culture gave 32.5 f 5.2 (SD) pmol cAMP per culture and the peripheral plasma of the patient gave 22.0 f 4.5 (SD) pmol cAMP per culture. The control value obtained by adding pooled plasma from normal subjects was 11.5 f 3.8 pmol cAMP/culture. The P value between all pairs was < 0.05.

Discussion

The clinical course of the patient strongly suggests that the renal carcinoma was secreting a humoral factor re- sponsible for the hypercalcaemia. The bioassay results confirmed the presence in the circulation of a high level of bioactivity capable of stimulating cAMP in bone cells and originating in the tumour. The absence of immuno- reactive PTH, even from the renal vein, indicated that the substance had a structure different from PTH. The possibility that cAMP production by the tumour [7] contributed to the result is excluded since only intra- cellular bone-cell cAMP was measured.

If, as seems likely, the factor in the patient’s blood causing stimulation of bone-cell adenylate cyclase was also responsible for the hypercalcaemia, we can draw further conclusions. The marked gradient found at the tumour effluent vein (especially such a large vein), and the rapid return of serum calcium to normal following tumour removal both imply a relatively short half-life for the substance in the circulation. Of the identified factors other than PTH which cause humoral hypercal- caemia, only prostaglandins markedly stimulate cAMP [%lo]. Moreover, production of prostaglandins by renal carcinomas in vivo [ 1 1 1 and in vitro [ 121 has recently been shown. However, it is possible that another as yet unidentified factor may be responsible for the hypercalcaemia. A vitamin D like substance is less likely because of longer duration of effect, and also because vitamin D and its metabolites have been shown not to cause stimulation of bone-cell adenylate cyclase [6, 8, 131.

Acknowledgments

The work was supported by grants from St Luke’s Cancer Research Fund and the Irish Cancer Society. We

thank Dr J . G. Kirker for permission to study the patient under his care, and Dr J . T. Potts, Jr, Massachusetts General Hospital, Boston, for a gift of PTH antiserum GP-I.

References

1 Powell D., Singer F.R., Murray T.M., Minkin C. & Potts J.T., Jr (1973) Nonparathyroid humoral hypercalcaemia in patients with neoplastic diseases. N Engl J Med 289, 176- 181.

2 Seyberth H.W., Segre G.V., Morgan J.L., Sweetman B.J., Potts J.T., Jr & Oates J.A. (1975) Prostaglandins as medi- ators of hypercalcaemia associated with certain types of cancer. NEnglJMed 293,1278-1283.

3 Seyberth H.W., Raisz L.G. & Oates J.A. (1978) Prostaglan- dins and hypercalcaemic states. Annu Rev Med 29,23-29.

4 Robertson R.P., Baylink D.J., Marini J.J. & Adkison H.W. (1975) Elevated prostaglandins and suppressed parathyroid hormone associated with hypercalcaemia and renal cell carci- noma. JClin EndocrinolMetab 41,164-167.

5 Segre G.V., Habener J.F., Powen D., Tregear G.W. & Potts J.T., Jr (1972) Parathyroid hormone in human plasma. Immunochemical characterization and biological implica- tions. JClin Invest 5 1 , 3163-3172.

6 McPartlin J . & Powell D. (1976) A bioassay for parathyroid hormone and other hypercalcaemic substances. Ir J Med Sci

7 Hunt N.H., Shortland J.R., Michelangeli V.P., Hammonds J.C., Atkins D. & Martin T.J. (1978) Adenylate cyclase ac- tivity of renal cortical carcinomas and its relation to histo- logy and ultrastructure. Cancer Res 38,23-31.

8 Chase L.R., Fedak S.A. & Aurbach G.D. (1969) Activation of skeletal adenyl cyclase by parathyroid hormone in vitro. Endocrinology 84,761-768.

9 Klein D.C. & Raisz L.G. (1970) Prostaglandins: stimulating of bone resorption in tissue culture. Endocrinology 86, 1436- 1440.

10 Raisz L.G., Luben R.A., Mundy G.R., Dietrich J.W., Horton J.E. & Trummel C.L. (1975) Effect of osteoclast activating factor from human leukocytes on bone metabolism. J Clin Invest 56,408-413.

11 Cummings K.B. & Robertson R.P. (1977) Prostaglandin: increased production by renal cell carcinoma. J Urol 118,

12 Atkins D., Ibbotson K.J. , Hillier K., Hunt N.H., Hammonds J.C. & Martin T.J. (1977) Secretion of prostaglandins as bone-resorbing agents by renal cortical carcinoma in culture. Br JCancer 36,601-607.

13 Mahgoub A. & Sheppard H. (1975) Early effect of 25- hydroxycholecalciferol (25 NCC) and 1,25 dihydroxychole- calciferol on the ability of parathyroid hormone (PTH) to elevated cyclic AMP of intact bone cells. Biochem Biophys Res Commun 62,901-907.

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European Journal of Clinical Investigation (1978) 8,427

The Editors are grateful to the following for generously giving of their time for careful appraisal of the manuscripts submitted for the eighth volume of the European Journal of Clinical Investigation.

K. G. M. M. Alberti, Southai M. E. Allison, Glasgow A. Angel, London A. W. Asscher, Cardiff G. L. Atkins, Edinburgh J. D. Baird, Edinburgh E. 0. Balasse, Brussels M. Besser, London J. Bernal, Madrid R. F. Bing, Sheffield E. L. Blair, Newcastle I. A. D. Bouchier, Dundee G. S. Boyd, Edinburgh A. Breckenridge, Liverpool D. Briggs, Glasgow J. J . Brown, Glasgow P. W. Brunt, Aberdeen K. Buchanan, Belfast C. W. Burke, Oxford G. F. Cahill, Boston J. S. Cameron, London S. Cameron, London L. A. Carlson, Stockholm M. E. Carruthers, London W. R. Cattell, London V. Chadwick, London T. M. Chalmers, Edinburgh M. Clarkson, Liverpool J. G. Collee, Edinburgh J. G. Collier, London J . S. Comaish, Newcastle A. R. Constable, London G. Curzon, London K. Davidson, Edinburgh A. Davies, Leeds A. M. Davison, Leeds A. Dawson, London J. L. Dawson, London A. St.J. Dixon, Bath N. J. Douglas, Edinburgh R. H. Dowling, London J. Doyle, Edinburgh C. R. W. Edwards, London S. Erlinger, Clichy D. R. Eyre, Boston G. S. Fell, Glasgow C. T. G. Flear, Newcastle F. V. Flynn, London P. Freychet, Nice E. R. Froesch, Zurich J . S. Garrow, Harrow B. Gribbin, Oxford D. R. Hadden, Belfast C. N. Hales, Cambridge

npton R. Hall, Newcastle J . J. E. Hankiss, Hungary F. D. Hart, London R. F. Harvey, Bristol W. R. Hazzard, London K. Hearn, Manchester D. J . Hearse, London T. J . C. Higgins, Macclesfield J . J . Hoet, Brussels G. Holdsworth, London E. Housley, Edinburgh B. Hulme , London L. Hume, Edinburgh D. Hunt, London J . A. A. Hunter, Edinburgh H. S. Jacobs, London 0. James, Newcastle R. J . Jarrett, London A. Kappas, New York R. Kellet, Edinburgh H. Kohler, Mainz A. Kurtz, London A. T. Lambie, Edinburgh A. G. h i t c h , Cincinnati C. L. Long, Toledo R. Lorimer, Glasgow T. S. Low-Beer, Birmingham G. Lowe, Glasgow K. Lundholm, Gothenburg R. Mahler, Cardiff N. P. Mallick, Manchester K. L. Manchester, Johannesburg A. M. Martin, Sunderland J . D. Maxwell, London T. Meade, London U. A. Meyer, Zurich K. Morris, Nottingham A. Mowat, Aberdeen M. G. McGeown, Belfast N. McIntyre, London A. E. M. McLean, London P. J . Nestel, Prahran B. E. C. Nordin, Leeds J. Norman, Southampton W. Oelkers, Berlin D. Ogston, Aberdeen L. H. Opie, Pisa J. H. Ottaway, Edinburgh I. J . T. Parboosingh, Edinburgh A, Parker, Edinburgh T. G. Parks, Belfast R. Passmore, Edinburgh C. R. Paterson, Dundee G. Paumgartner, Berne

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