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Open access

Andrew R Tang, Laura E Hinz, Aneal Khan, and Gregory A Kline

Summary

Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare, autosomal recessive disorder caused by mutations in the SLC34A3 gene that encodes the renal sodium-dependent phosphate cotransporter 2c (NaPi-IIc). It may present as intermittent mild hypercalcemia which may attract initial diagnostic attention but appreciation of concomitant hypophosphatemia is critical for consideration of the necessary diagnostic approach. A 21-year-old woman was assessed by adult endocrinology for low bone mass. She initially presented age two with short stature, nephrocalcinosis and mild intermittent hypercalcemia with hypercalciuria. She had no evidence of medullary sponge kidney or Fanconi syndrome and no bone deformities, pain or fractures. She had recurrent episodes of nephrolithiasis. In childhood, she was treated with hydrochlorothiazide to reduce urinary calcium. Upon review of prior investigations, she had persistent hypophosphatemia with phosphaturia, low PTH and a high-normal calcitriol. A diagnosis of HHRH was suspected and genetic testing confirmed a homozygous c.1483G>A (p.G495R) missense mutation of the SLC34A3 gene. She was started on oral phosphate replacement which normalized her serum phosphate, serum calcium and urine calcium levels over the subsequent 5 years. HHRH is an autosomal recessive condition that causes decreased renal reabsorption of phosphate, leading to hyperphosphaturia, hypophosphatemia and PTH-independent hypercalcemia due to the physiologic increase in calcitriol which also promotes hypercalciuria. Classically, patients present in childhood with bone pain, vitamin D-independent rickets and growth delay. This case of a SLC34A3 mutation illustrates the importance of investigating chronic hypophosphatemia even in the presence of other more common electrolyte abnormalities.

Learning points:

  • Hypophosphatemia is an important diagnostic clue that should not be ignored, even in the face of more common electrolyte disorders.
  • HHRH is a cause of PTH-independent hypophosphatemia that may also show hypercalcemia.
  • HHRH is a cause of hypophosphatemic nephrocalcinosis that should not be treated with calcitriol, unlike other congenital phosphate wasting syndromes.
  • Some congenital phosphate wasting disorders may not present until adolescence or early adulthood.
Open access

Maryam Heidarpour, Mehdi Karami, Pegah Hedayat, and Ashraf Aminorroaya

Summary

Primary hyperparathyroidism revealed by thoracic spine brown tumor and peptic ulcer bleeding is rare. We presented a case of 33-year-old male patient who was admitted with paraplegia. Thoracic spine magnetic resonance imaging (MRI) showed extradural lesion at T4 level. He underwent surgical decompression in T4. According to histopathologic finding and elevated serum parathormone (PTH) and hypercalcemia (total serum calcium 12.1 mg/dL), the diagnosis of brown tumor was down. Ultrasonography of his neck showed a well-defined lesion of 26 × 14 × 6 mm. The day after surgery, he experienced 2 episodes of melena. Bedside upper gastrointestinal endoscopy showed gastric peptic ulcer with visible vessel. Treatment with intragastric local instillation of epinephrine and argon plasma coagulation was done to stop bleeding. After stabilization of the patient, parathyroidectomy was performed. Histologic study showed the parathyroid adenoma without any manifestation of malignancy. At discharge, serum calcium was normal (8.6 mg/dL). On 40th day of discharge, standing and walking status was normal.

Learning points:

  • Thoracic spine involvement is a very rare presentation of primary hyperparathyroidism.
  • The issue of whether primary hyperparathyroidism increases the risk of peptic ulcer disease remains controversial. However, gastrointestinal involvement has been reported in association with classic severe primary hyperparathyroidism.
  • The treatment of brown tumor varies from case to case.
Open access

Christopher Muir, Anthony Dodds, and Katherine Samaras

Summary

Diamond–Blackfan anaemia (DBA) is a rare cause of bone marrow failure. The incidence of malignancy and endocrine complications are increased in DBA, relative to other inherited bone marrow failure syndromes. We describe an adult woman with DBA who developed osteoporosis and avascular necrosis (AVN) of both distal femora. Such endocrine complications are not uncommon in DBA, but under-appreciated, especially in adulthood. Further, rectal adenocarcinoma was diagnosed at age 32 years, requiring hemi-colectomy and adjuvant chemotherapy. Elevated cancer risk may warrant disease-specific screening guidelines. Genetic predictors of extra-haematopoetic complications in DBA are yet to be established.

Learning points:

  • Endocrine complications are common in DBA.
  • Clinical vigilance is required in managing bone health of DBA patients treated with glucocorticoids.
  • There is currently no reliable way to predict which patients will develop complications of therapy or premature malignancy related to DBA.
  • Complaints of bone or joint pain should prompt screening with targeted magnetic resonance imaging. Osteoporosis screening should be performed routinely.
Open access

Clement Olukayode Aransiola and Arinola Ipadeola

Summary

Paget's disease is a chronic and progressive disorder of bone characterized by focal areas of excessive osteoclastic resorption accompanied by a secondary increase in the osteoblastic activity. Paget's disease of bone (PBD) is a rare endocrine disease especially among Africans and Asians. Hence the detection of a case in a middle-aged Nigerian is of interest. We present the case of a 62-year-old Nigerian man in apparent good health who was found to have a markedly elevated serum total alkaline phosphatase (ALP) of 1179 U/l (reference range, 40–115 U/l) 4 years ago during a routine medical check-up in the USA. He had no history suggestive of PDB and also had no known family history of bone disease. Examination findings were not remarkable except for a relatively large head. A repeat ALP in our centre was 902 U/l (reference range, 40–120 U/l). Cranial CT scan showed diffuse cranial vault thickening consistent with Paget's disease which was confirmed by Tc-99m hydroxymethylene diphosphonate. He was placed on 40 mg alendronate tablets daily for 6 months. The patient has remained asymptomatic and has been in continuing biochemical remission during the 3-year follow-up period. The most recent ALP result is 88 U/l (reference range, 30–132 U/l) in April 2015.

Learning points

  • Serum total alkaline phosphatase remains a sensitive marker of bone turnover and an isolated increase above the upper limit of normal warrants more intense scrutiny in form of investigations targeted at excluding PD.
  • Paget's disease is very rare but can occur in the Africans as seen in this Nigerian man and most patients are asymptomatic.
  • Asymptomatic patients can benefit from treatment if disease is active, polyostotic or the lesions are located in bones with future risk of complications such as long bones, vertebrae and skull.
  • Bisphosphonates are still the mainstay of treatment and alendronate is a useful therapeutic option for treatment.