Admit the person if they are symptomatic or have severe hypercalcaemia

• This recommendation is based on expert opinion from a narrative review [Smellie et al, 2008].

Repeat the serum calcium concentration after 1 week

• This recommendation is based on the opinion of a CKS expert reviewer.

Urgently refer if cancer is suspected

• This is based on Referral guidelines for suspected cancer from the National Institute for Health and Clinical Excellence (NICE) [NICE, 2005] (see the CKS topics in the clinical speciality on Cancer - suspected (NICE referral advice)), as well as narrative reviews [Ralston et al, 2004; Murphy et al, 2006].

Refer to an endocrinologist if familial hypocalciuric hypercalcaemia is suspected

• This recommendation is based on international guidelines on the management of primary hyperparathyroidism [Bilezikian et al, 2009]. Primary hyperparathyroidism must be excluded, and familial hypocalciuric hypercalcaemia needs to be confirmed by 24-hour urinary calcium levels.

Refer people with known renal failure to their renal specialist

• This is based on a NICE guideline on the management of chronic kidney disease in adults in primary and secondary care [National Collaborating Centre for Chronic Conditions, 2008]. See the CKS topic on Chronic kidney disease - not diabetic.

Consider admitting to hospital or referring urgently to a renal specialist those people with renal failure that was not previously known

• This recommendation is based on what CKS considers to be good clinical practice and comments from a CKS expert reviewer.

Stop any drugs contributing to hypercalcaemia if appropriate and recheck the serum calcium

• This recommendation is based on expert opinion from a narrative review [Bushinsky and Monk, 1998].
• The recommendation to consider admitting people with suspected milk-alkali syndrome is based on expert opinion from a narrative review, that correction of fluid and electrolyte abnormalities may be needed [Chan et al, 1997].
• The recommendation to contact the person's mental health specialist if they are taking lithium, in order to discuss whether to stop the lithium, monitor the serum calcium, or refer to an endocrinologist, is based on expert opinion from a narrative review [Jones and Twomey, 2009]. The authors state that management options for lithium-induced hypercalcaemia include:
• Discontinuing lithium, after which hypercalcaemia generally resolves.
• Continuing lithium, with regular monitoring, if hypercalcaemia is mild and asymptomatic.
• Surgical parathyroid exploration when lithium cannot be discontinued or calcium levels do not decrease after it has been discontinued for an appropriate time.
• Hypercalcaemia due to vitamin D ingestion may take many weeks to correct because of the long elimination half-life (10–20 days) of 25-hydroxyvitamin D [Barth et al, 2008].
• The recommendation to look for another underlying cause or refer the person to an endocrinologist or other appropriate specialist if the adjusted serum calcium level remains high after discontinuation of the drug, is based on what CKS considers to be good clinical practice. It is also based on evidence from narrative reviews that primary hyperparathyroidism is the most common cause of hypercalcaemia in the community [Chan et al, 1997; Bushinsky and Monk, 1998], particularly when hypercalcaemia is mild [Bilezikian, 1993].

Refer to an endocrinologist if non-parathyroid endocrine disease is suspected

• Non-parathyroid endocrine diseases that can cause hypercalcaemia usually need specialist investigation and management.

Immobilization in Paget's disease

• In the absence of trial-based evidence, the recommendation to address the immobilization, if possible, and monitor the person's serum calcium concentration is based on what CKS considers to be good practice.
• The recommendation to refer the person to a specialist if mobilization is not possible or the person's serum calcium concentration remains high is based on evidence that oral or intravenous bisphosphonates are effective and should be prescribed. This evidence is from an observational study and expert opinion in a UK guideline on the management of Paget's disease of bone (from the Bone and Tooth Society of Great Britain and the National Association for the Relief of Paget's Disease) [Selby et al, 2002] and narrative reviews [Siris et al, 2006; Ralston et al, 2008]. Referral as opposed to treatment in primary care is recommended on the basis of expert opinion in a published letter (responding to the guideline) that hypercalcaemia in Paget's disease is more likely to be due to coexisting primary hyperparathyroidism, that bisphosphonates increase parathyroid hormone levels, and therefore primary hyperparathyroidism should be excluded prior to starting a bisphosphonate [Gutteridge, 2006].

Refer the person to a respiratory specialist (or other specialist, depending on disease manifestation) if sarcoidosis is suspected

• This recommendation is based on what CKS considers to be appropriate referral pathways and on expert opinion from a narrative review on the primary care management of sarcoidosis [Wu and Schiff, 2004].

Refer to an endocrinologist if a cause is not clear

• This recommendation is made on the basis that an endocrinologist is most likely to have the expertise to determine the cause.