Hypercalcemia is common in patients after kidney transplantation (KTx) and is associated with persistent hyperparathyroidism in the majority of cases. This retrospective, single-center study evaluated the prevalence of hypercalcemia after KTx. KTx recipients were evaluated for 7 years after receiving kidneys from living or deceased donors. A total of 301 patients were evaluated; 67 patients had hypercalcemia at some point during the follow-up period. The median follow-up time for all 67 patients was 62 months (44; 80). Overall, 45 cases of hypercalcemia were classified as related to persistent post-transplant hyperparathyroidism (group A), 16 were classified as “transient post-transplant hypercalcemia” (group B), and 3 had causes secondary to other diseases (1 related to tuberculosis, 1 related to histoplasmosis, and 1 related to lymphoma). The other 3 patients had hypercalcemia of unknown etiology, which is still under investigation. In group A, the onset of hypercalcemia after KTx was not significantly different from that of the other groups, but the median duration of hypercalcemia in group A was 25 months (12.5; 53), longer than in group B, where the median duration of hypercalcemia was only 12 months (10; 15) (P<0.002). The median parathyroid hormone blood levels around 12 months after KTx were 210 pg/mL (141; 352) in group A and 72.5 pg/mL (54; 95) in group B (P<0.0001). Hypercalcemia post-KTx is not infrequent and its prevalence in this center was 22.2%. Persistent hyperparathyroidism was the most frequent cause, but other important etiologies must not be forgotten, especially granulomatous diseases and malignancies.

It is well recognized that stressful experiences promote robust emotional memories, which are well remembered. The amygdaloid complex, principally the basolateral complex (BLA), plays a pivotal role in fear memory and in the modulation of stress-induced emotional responses. A large number of reports have revealed that GABAergic interneurons provide a powerful inhibitory control of the activity of projecting glutamatergic neurons in the BLA. Indeed, a reduced GABAergic control in the BLA is essential for the stress-induced influence on the emergence of associative fear memory and on the generation of long-term potentiation (LTP) in BLA neurons. The extracellular signal-regulated kinase (ERK) subfamily of the mitogen-activated protein kinase (MAPK) signaling pathway in the BLA plays a central role in the consolidation process and synaptic plasticity. In support of the view that stress facilitates long-term fear memory, stressed animals exhibited a phospho-ERK2 (pERK2) increase in the BLA, suggesting the involvement of this mechanism in the promoting influence of threatening stimuli on the consolidation fear memory. Moreover, the occurrence of reactivation-induced lability is prevented when fear memory is encoded under intense stressful conditions since the memory trace remains immune to disruption after recall in previously stressed animals. Thus, the underlying mechanism in retrieval-induced instability seems not to be functional in memories formed under stress. All these findings are indicative that stress influences both the consolidation and reconsolidation fear memory processes. Thus, it seems reasonable to propose that the emotional state generated by an environmental challenge critically modulates the formation and maintenance of long-term fear memory.