Systemic granulomatosis and hypercalcaemia following intravesical bacillus Calmette-Guérin immunotherapy

Rare Causes of Hypercalcemia: 2021 Update

CONTEXT

Primary hyperparathyroidism and malignancy are the etiologies in 90% of cases of hypercalcemia. When these entities are not the etiology of hypercalcemia, uncommon conditions need to be considered. In 2005, Jacobs and Bilezikian published a clinical review of rare causes of hypercalcemia, focusing on mechanisms and pathophysiology. This review is an updated synopsis of rare causes of hypercalcemia, extending the observations of the original article.

EVIDENCE ACQUISITION

Articles reporting rare associations between hypercalcemia and unusual conditions were identified through a comprehensive extensive PubMed-based search using the search terms "hypercalcemia" and "etiology," as well as examining the references in the identified case reports. We categorized the reports by adults vs pediatric and further categorized the adult reports based on etiology. Some included reports lacked definitive assessment of etiology and are reported as unknown mechanism with discussion of likely etiology.

EVIDENCE SYNTHESIS

There is a growing understanding of the breadth of unusual causes of hypercalcemia. When the cause of hypercalcemia is elusive, a focus on mechanism and review of prior reported cases is key to successful determination of the etiology.

CONCLUSIONS

The ever-expanding reports of patients with rare and even unknown mechanisms of hypercalcemia illustrate the need for continued investigation into the complexities of human calcium metabolism.

Vitamin D-Mediated Hypercalcemia: Mechanisms, Diagnosis, and Treatment

Hypercalcemia occurs in up to 4% of the population in association with malignancy, primary hyperparathyroidism, ingestion of excessive calcium and/or vitamin D, ectopic production of 1,25-dihydroxyvitamin D [1,25(OH)₂D], and impaired degradation of 1,25(OH)₂D. The ingestion of excessive amounts of vitamin D₃ (or vitamin D₂) results in hypercalcemia and hypercalciuria due to the formation of supraphysiological amounts of 25-hydroxyvitamin D [25(OH)D] that bind to the vitamin D receptor, albeit with lower affinity than the active form of the vitamin, 1,25(OH)₂D, and the formation of 5,6-trans 25(OH)D, which binds to the vitamin D receptor more tightly than 25(OH)D. In patients with granulomatous disease such as sarcoidosis or tuberculosis and tumors such as lymphomas, hypercalcemia occurs as a result of the activity of ectopic 25(OH)D-1-hydroxylase (CYP27B1) expressed in macrophages or tumor cells and the formation of excessive amounts of 1,25(OH)₂D. Recent work has identified a novel cause of non-PTH-mediated hypercalcemia that occurs when the degradation of 1,25(OH)₂D is impaired as a result of mutations of the 1,25(OH)₂D-24-hydroxylase cytochrome P450 (CYP24A1). Patients with biallelic and, in some instances, monoallelic mutations of the CYP24A1 gene have elevated serum calcium concentrations associated with elevated serum 1,25(OH)₂D, suppressed PTH concentrations, hypercalciuria, nephrocalcinosis, nephrolithiasis, and on occasion, reduced bone density. Of interest, first-time calcium renal stone formers have elevated 1,25(OH)₂D and evidence of impaired 24-hydroxylase-mediated 1,25(OH)₂D degradation. We will describe the biochemical processes associated with the synthesis and degradation of various vitamin D metabolites, the clinical features of the vitamin D-mediated hypercalcemia, their biochemical diagnosis, and treatment.

Vaccines, adjuvants and autoimmunity

Vaccines and autoimmunity are linked fields. Vaccine efficacy is based on whether host immune response against an antigen can elicit a memory T-cell response over time. Although the described side effects thus far have been mostly transient and acute, vaccines are able to elicit the immune system towards an autoimmune reaction. The diagnosis of a definite autoimmune disease and the occurrence of fatal outcome post-vaccination have been less frequently reported. Since vaccines are given to previously healthy hosts, who may have never developed the disease had they not been immunized, adverse events should be carefully accessed and evaluated even if they represent a limited number of occurrences. In this review of the literature, there is evidence of vaccine-induced autoimmunity and adjuvant-induced autoimmunity in both experimental models as well as human patients. Adjuvants and infectious agents may exert their immune-enhancing effects through various functional activities, encompassed by the adjuvant effect. These mechanisms are shared by different conditions triggered by adjuvants leading to the autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome). In conclusion, there are several case reports of autoimmune diseases following vaccines, however, due to the limited number of cases, the different classifications of symptoms and the long latency period of the diseases, every attempt for an epidemiological study has so far failed to deliver a connection. Despite this, efforts to unveil the connection between the triggering of the immune system by adjuvants and the development of autoimmune conditions should be undertaken. Vaccinomics is a field that may bring to light novel customized, personalized treatment approaches in the future.

Rare causes of calcitriol-mediated hypercalcemia: a case report and literature review

CONTEXT

Calcitriol-mediated hypercalcemia resulting from elevated extrarenal 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-hydroxylase) activity has not previously been described in giant cell polymyositis.

CASE

We report an unusual case of hypercalcemia due to disseminated granulomatous disease in a 62-yr-old woman with profound proximal muscle weakness and weight loss. She was initially diagnosed with vitamin D deficiency myopathy with a low serum 25-hydroxyvitamin D; serum calcium at this time was low-normal. Vitamin D(3) 3000 IU daily was prescribed. One month later, blood work showed new hypercalcemia and hypercalciuria with normalized 25-hydroxyvitamin D. 1,25-dihydroxyvitamin D was high-normal, despite a suppressed PTH, undetectable PTHrP, and essentially normal renal function. Her hypercalcemia resolved, and her strength improved only after prednisone was added to bisphosphonate therapy. Two weeks later, she died from acute congestive heart failure.

METHODS AND RESULTS

Autopsy revealed a disseminated giant cell myositis affecting skeletal, cardiac, and gastrointestinal smooth muscle. Immunohistochemistry localized 1alpha-hydroxylase to the inflammatory infiltrates in skeletal and cardiac muscle.

EVIDENCE

A review of English publications in Medline and Embase, including a reference search of retrieved articles, revealed that calcitriol-mediated hypercalcemia has been described in over 30 conditions, most of which are granulomatous in nature, ranging from inflammatory conditions and foreign body exposures to infections and neoplasms.

CONCLUSIONS

Hypercalcemia resulting from autonomous 1alpha-hydroxylase activity may be unmasked by low-dose vitamin D supplementation and should not be excluded from the differential diagnosis of nonparathyroid causes if the serum calcitriol is inappropriately normal, rather than frankly elevated.

[Non-tuberculous systemic granulomatosis mimicking sarcoidosis but related to a specific etiology. Study of 67 cases]

PURPOSE

Systemic granulomatosis (SG) are frequently encountered in internal medicine. Despite a large list of aetiologies, the investigations remain often negative leading to the diagnosis of atypical sarcoidosis. The spectrum of the causes, as well as evolution of these SG is not clearly delineated in the literature.

METHOD

We analyzed the case reports of all but tuberculous GS submitted at the National Meetings of the National French Society of Internal Medicine from 1990 to 2006.

RESULTS

Sixty-seven cases were included in the study. The average age at the beginning of the symptoms was 47.8 years and 28.4% of the patients were female. The median diagnostic delay was one year. General symptoms were present in 73.1% of the cases. The involved organs were the liver (46.3%), lungs (25.4%), lymph nodes (22.4%), digestive tract (16.4%), skin (16.4%), spleen (14.9%). The granuloma were detected mainly in the liver (38.8%), lymph nodes (17.9%), bone marrow (16.4%) and lungs (11.9%). Elevated erythrocyte sedimentation rate or increased C reactive protein serum levels were noted in 65.6% of the patients. Before diagnosis, 19.4% of the patients received a corticotherapy. The most common diagnoses were infections (65.6%) followed by drugs (19.5%), "toxic substances" or various foreign bodies (5.9%), neoplasias (5.9%) and immune deficiencies (3%). The evolution was favourable in 80% of the cases but 8.3% of the patients died. The disease course of the patients having received a corticotherapy prior to the diagnosis was more unfavourable with a death rate of 45%.

CONCLUSION

In atypical sarcoidosis (fever, advanced age, increased acute phase reactants...) a specific aetiology and especially an infectious disease should be ruled out before considering the diagnosis of sarcoidosis. Corticotherapy is a factor of poor prognosis.

Osteoarticular side effects of BCG therapy

Although osteoarticular side effects of the Bacillus Calmette-Guérin (BCG) are rare compared to the number of administrations, BCG vaccination and cancer therapy are so widely used that the absolute number of cases is not negligible. Osteoarticular infection is an exceedingly rare complication of vaccination with the BCG. Intravesical BCG instillations used to treat superficial bladder cancer may cause arthralgia, reactive arthritis or osteoarticular infections. Intradermal BCG therapy used to treat a number of malignancies can cause osteoarticular infections or bilateral symmetric polyarthritis predominating in the wrists and fingers. In practice, when intravesical BCG instillation is followed by arthritis, hyperthermia is unhelpful for distinguishing septic arthritis from reactive arthritis. Arguments pointing to reactive arthritis include oligo- or polyarticular involvement and onset a few weeks (as opposed to a few months) after the last instillation. Nevertheless, joint fluid examination is in order to rule out septic arthritis. BCG-induced reactive arthritis usually responds well to nonsteroidal anti-inflammatory drugs. Osteoarticular infections related to BCG therapy should be treated by rifampin, isoniazid and ethambutol for 2 months, followed by rifampin and isoniazid for 10 months.

Clinical review: Rare causes of hypercalcemia

CONTEXT

Although hypercalcemia is usually caused by primary hyperparathyroidism or malignancy, a number of other conditions can be important to consider. This review considers unusual causes of hypercalcemia that are generally not found in reviews on this subject.

EVIDENCE ACQUISITION

Articles describing rarely reported associations between hypercalcemia and unusual causes were identified through a computer search of the terms hypercalcemia/etiology and through the references listed in those articles. We grouped the 58 different reports into categories defined by a presumed etiology: increased levels of 1,25-dihydroxyvitamin D or PTHrP, occult milk-alkali syndrome, and undefined mechanisms. Reports in infants and children are listed separately, as are reports of pseudohypercalcemia, situations that are not truly hypercalcemic because the ionized calcium is normal.

EVIDENCE SYNTHESIS

In some situations, as this review points out, a number of unusual causes of hypercalcemia are important to consider. The search for an elusive cause of hypercalcemia is best accomplished by the most likely potential mechanism. An orderly search in this manner is likely to reveal the underlying cause.

CONCLUSIONS

That so many patients have been described with rare and usually poorly understood causes of hypercalcemia highlights our incomplete understanding of calcium metabolism in humans and suggests additional areas in which directed clinical investigation might improve our knowledge of the normal metabolism of calcium.