Hyperkalemia

Definition
Pathogenesis
Causes
Management & Determining the Cause
Study Question

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A 65-year-old man presents to the clinic complaining of progressive dyspnea, hemoptysis, and 10 kg weight loss over the past 6 months. The patient also reports intermittent abdominal pain, nausea, and headache over the past week. Past medical history is significant for hypertension and tobacco use disorder (40-pack-years). Laboratory studies include sodium 140 mEq/L, potassium 3.7 mEq/L, chloride 103 mEq/L, calcium 13 mg/dL, phosphorus 1.8 mg/dL, BUN 15 mg/dL, creatinine 0.9 mg/dL, and hemoglobin 14.4 g/dL. Which of the following is most likely responsible for the patient's lab abnormalities?

1. Squamous cell carcinoma
2. Parathyroid adenoma
3. Small cell lung carcinoma
4. Renal cell carcinoma

The correct answer is 1.

Hypercalcemia of malignancy is the most common cause of rapidly progressive hypercalcemia. Symptoms, if present, include nausea, vomiting, headache, altered mental status, confusion, abdominal pain, constipation, myalgias, and polyuria.
Hypercalcemia of malignancy is commonly due to a paraneoplastic syndrome. The most common of these is the release of parathyroid-related-peptide (PTHrP) by the primary tumor. Squamous cell carcinomas commonly release this compound, but it can also be seen in other solid tumors involving the genitourinary tract. Other causes of hypercalcemia of malignancy include ectopic vitamin D production due to increased 1-alpha-hydroxylase activity and osteolytic bone metastasis.
PTHrP is classically released from squamous cell carcinomas. It mimics the parathyroid hormone in structure and function. Negative feedback is uncommon and as a result, significant elevations in serum calcium can be seen.
Renal cell carcinomas may secrete PTHrP. Renal cell carcinomas classically present with painful hematuria in a chronic tobacco user. Parathyroid adenomas are the most common cause of primary hyperparathyroidism. Small cell lung carcinomas are associated with several paraneoplastic syndromes including SIADH, ectopic ACTH, and Lambert-Eaton syndrome.

StatPearls Topic: Physiology, Calcium

PubMed: Physiology, Calcium

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Classifications:

AnatomicalScience:

Endocrine and Metabolic, Oncologic, Pulmonary

Clinical Sciences:

Causes, Differential, Evaluation Lab, History Physical

Client Need Sciences:

Physiological Adaptation (Care Ill Patients)

Cognitive Ability Level:

3-Application (Knowledge Use in Care)

Integrated Processes:

Process (Analysis, Assess, Eval, Implement, Plan)

PubMed References

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The Relationship of Physical Activity and Anthropometric and Physiological Characteristics to Bone Mineral Density in Postmenopausal Women., Arazi H,Eghbali E,Saeedi T,Moghadam R,, Journal of clinical densitometry : the official journal of the International Society for Clinical Densitometry, 2016 Feb 24 [PubMed PMID: 26922458]

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Rodríguez AJ,Scott D,Khan B,Hodge A,English DR,Giles GG,Abrahamsen B,Ebeling PR, High calcium intake in men not women is associated with all-cause mortality risk: Melbourne Collaborative Cohort Study. Archives of osteoporosis. 2018 Sep 21; [PubMed PMID: 30242518]

Vassallo P,Green N,Courtney E, Hypercalcemia secondary to excessive self-medication with antacids causing acute pancreatitis: a case report. Croatian medical journal. 2019 Feb 28; [PubMed PMID: 30825277]

Hypercalcemia