Sixty-Two-Year-Old Male Suffering From Uremic Leontiasis Ossea Caused by Severe Secondary Hyperparathyroidism

Pharmacogenetic and safety analysis of cinacalcet hydrochloride in healthy Chinese subjects

BACKGROUND

Our study aims to explore the effect of genetics on the pharmacodynamics (PD) and pharmacokinetics (PK) of cinacalcet in healthy Chinese subjects; to investigate the effect of dietary factors on cinacalcet, and to evaluate the safety of cinacalcet under fasting and non-fasting conditions using a bioequivalence trial.

METHODS

We investigated the relationship of cinacalcet PK with single nucleotide polymorphisms (SNPs) of CYP3A4, CYP1A2 and CYP2D6, and of cinacalcet PD with SNPs of calcium-sensitive receptors (CASR) and vitamin D receptors (VDR) in 65 healthy Chinese subjects recruited to participate in this study. Our study was a phase I, open-label, randomized, two-period, two-sequence crossover, a single-center clinical study designed under both fasting and non-fasting conditions to investigate the effect of dietary factors on cinacalcet. Plasma cinacalcet concentrations were analyzed using a validated HPLC-MS/MS assay. Clinical laboratory tests evaluated safety. Thirteen SNPs of CASR, VDR, and CYP genes were selected for pharmacogenetic analysis.

RESULTS

CYP3A4 rs4646437 was found to be associated with the PK of cinacalcet under fasting conditions (P<0.01). Subjects carrying T alleles of rs4646437 appeared to metabolize cinacalcet poorly. The C_max and AUC of subjects in the non-fasting group were significantly higher (P<0.0001) than those in the fasting group. The T_max, CL/F, and Vd/F in the fasting group were significantly higher (P<0.0001) than those in the non-fasting group. In the fasting group, the geometric least square mean ratios (T/R) of the C_max and AUC_0-t were 109.89% and 105.33%, and the corresponding 90% CIs were 98.36-122.79% and 98.04-113.15%, respectively. In the non-fasting group, the T/R of the C_max and AUC_0-t were 100.74% and 99.09%, and the corresponding 90% CIs were 92.65-109.54% and 94.79-103.58%, respectively. All adverse events (AEs) were mild, and no serious adverse events (SAEs) occurred during the bioequivalence trial.

CONCLUSIONS

Following our investigation, we reached the following conclusions: CYP3A4 rs4646437 may affect cinacalcet PK; the reference and test preparations of cinacalcet were bioequivalent under fasting and non-fasting conditions and were safe to use; and dietary factors had a significant effect on the PK of cinacalcet, in that exposure to the drug increased when cinacalcet was taken after eating.

Uremic Leontiasis Ossea in a Patient With End-Stage Renal Disease in Hemodialysis

Uremic leontiasis ossea is a rare condition, reported in patients with severe renal disease. Patients present with progressive enlargement of facial bones - in particular, the maxillary and mandibular bones. Rarity of this condition leaves clinicians puzzled on initial evaluation and management. Herein, we present a 31-year-old man diagnosed with uremic leontiasis ossea. The report aims to review the pathophysiology of the condition as described in the literature, the patient presentation and imaging modalities used to investigate, and classical findings seen in patients with uremic leontiasis ossea. Finally, we briefly touch base on the reported regimens used to prevent and manage this condition.

Severe bone disease caused by primary hyperparathyroidism: a case report and review of the literature

Bone disease is an important complication of hyperparathyroidism. We herein report a rare case of severe bone disease caused by primary hyperparathyroidism. A 33-year-old man presented with pain and restricted mobility in his right upper limb and right hip due to a fall 3 days previously. X-ray examination showed a fracture of the proximal and distal humerus. Computed tomography examination showed a supracondylar fracture of the right humerus, a fracture of the right femoral neck, a fracture of the right sciatic branch, and multiple brown tumors. Ultrasonography showed a 3.5- × 1.6-cm hypoechoic mass below the left lobe of the thyroid. The patient was diagnosed with primary hyperparathyroidism based on increased serum calcium and parathormone concentrations, pathological fractures, and multiple brown tumors. He therefore underwent bilateral lower parathyroidectomy. Pathological examination revealed a parathyroid adenoma. The patient recovered well after surgery and was followed up for 6 months with no symptoms of hyperparathyroidism. This case report suggests that clinicians should be aware of the possibility of severe bone disease secondary to primary hyperparathyroidism. Active and early diagnosis and surgical treatment are important in such cases.

Uremic leontiasis ossea due to secondary hyperparathyroidism complicated by vitamin C deficiency in a non-adherent chronic hemodialysis patient: A case report

Non-adherence to medical therapy in patients with end-stage kidney disease (ESKD) can lead to severe metabolic derangements rarely seen in the current medical era. Such complications may take the form of secondary hyperparathyroidism (HPT) leading to rare manifestations of bone mineral disease, and profound vitamin C deficiency from poor nutrition combined with removal of water-soluble vitamins during dialysis. Secondary HPT causes renal osteodystrophy which can lead to diffuse enlargement of the facial skeleton and morphological changes suggestive of leontiasis ossea. We report a 36-year-old, non-adherent woman on chronic dialysis for over 10 years who developed progressive, diffuse facial bone enlargement in the context of years of extreme HPT and newly diagnosed severe vitamin C deficiency. Imaging revealed diffuse hypertrophy of the maxillary and mandibular bones. Histopathology showed extensive fibro-osseous proliferation without evidence of Brown tumor, suggestive of uremic leontiasis ossea. In this report, we discuss the orofacial manifestations of secondary HPT and the possible potentiating role of vitamin C deficiency on the development of renal osteodystrophy through altered vitamin D metabolism. Non-adherent patients on chronic dialysis should be evaluated for vitamin C deficiency, and the development of uremic leontiasis ossea should be considered when such patients present with distortion of facial features in the context of severe secondary HPT.