A case of primary hyperparathyroidism in an elderly patient who exhibited characteristic severe generalized pain: the second case report in the literature

Abstract

Primary hyperparathyroidism (PHPT) is an endocrine disorder in which adenoma, carcinoma, or hyperplasia develop in the parathyroid gland, leading to excessive parathyroid hormone secretion. It causes various physical and/or neuropsychiatric symptoms. PHPT is classified into three types in Japan: (i) the renal type, in which stones develop in the kidneys; (ii) the bone type, in which pathological fractures and osteitis fibrosa develop; and (iii) the biochemical type, which is discovered during routine biochemical laboratory examinations and does not involve kidney stones or bone disease. In patients with the biochemical type, various physical symptoms and psychiatric symptoms can develop. Neurocognitive disorder, which is regarded as a type of so-called ‘treatable dementia’, can also arise. Therefore, even in the biochemical type, patients who are suspected of having neurocognitive disorder or somatic symptom disorder may have to visit a psychiatric clinic, along with those who do develop psychiatric symptoms. Because of this potential, psychiatrists must be informed about PHPT. The pain caused by PHPT differs among the three types of the disease. In the renal type, pain can be caused by renal, ureteral, or urinary bladder stones. In the bone type, bone pain can be caused by skeletal deformities due to excessive bone resorption, such as the pathological fractures, osteitis fibrosa cystica, and osteoarthritis. Peripheral neuropathic pain can develop in cases of nerve compression. In contrast, in the biochemical type, bone pain seldom develops. In general, the mild osteopenia and osteoporosis seen in the biochemical type do not usually cause severe pain, except when a fracture occurs. I experienced a female case in her early 70s with PHPT who had various characteristic types of pain (Appendix S1). The characteristics of this case are summarized as follows: 1 A patient with biochemical-type PHPT manifested with several characteristic types of pain. 2 Characteristic types of pain were observed in various regions. For example, severe pain extended from the lower back to the lower extremities and persisted for several days; pain that felt like being pricked by needles affected the tongue and forearms; and sudden severe pain accompanied by itching and/or numbness arose in the lower extremities. Also, the patient experienced severe pain in her fingers when she touched water. 3 The characteristics of these types of pain seemed to differ from those of the nociceptive and/or peripheral neuropathic pain associated with pathological fractures, motor organ disorders, and spinal disease. 4 The various types of pain resembled central neuropathic pain, but they may have differed from the previously reported ‘organic’ central neuropathic pain because most of them rapidly improved after parathyroidectomy. I searched the literature for reports about cases of PHPT involving severe pain like that experienced by my patient and found only one similar case report. Sakaguchi et al. suggested that the severe generalized pain experienced by their patient might have been bone pain. However, no clear bone disease was observed, and the reasons why they thought it might be bone pain were not clearly described. How could the characteristic types of pain exhibited by the current patient have been generated? Were there multiple microfractures and/or small osteitis lesions in her bones? I consider that it is unlikely that microfractures or osteitis could explain the various types of pain that arose in the current patient or the severe generalized pain experienced by the patient described by Sakaguchi et al. I previously published a report about the association between Lewy body disease and chronic pruritus. In the report, I discussed the similarities and