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Hematology/Oncology > Hypercalcemia (3) > Flashcards

Hypercalcemia (3) Flashcards

1
Q

What is hypercalcemia defined as?

A

Serum calcium above the upper limit of normal…

Total calcium > 10.5 mg/dL
Ionized fraction calcium > 5.6 mg/dL

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2
Q

What is considered mild hypercalcemia?

A

Total calcium 10-12 mg/dL

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3
Q

What is considered moderate hypercalcemia?

A

Total calcium 12-14 mg/dL

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4
Q

What is considered severe hypercalcemia?

A

Total calcium > 14 mg/dL
-this is considered a crisis

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5
Q

Total vs ionized calcium

A

Total calcium is the TOTAL amount of calcium in the blood
It includes free and bound calcium
Normal levels are 8.6-10 mg/dL
And it is an easy/cheap lab to obtain (typically included in BMP)

Ionized calcium is the FREE calcium (calcium unbound to protein - active form)
This is tightly correlated to thyroid function
Normal levels are 4.64 - 5.28 mg/dL (about half of the total calcium)

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6
Q

What labs should be looked at in the initial workup? (6)

A
  1. Calcium (total and ionized)
  2. Albumin (because calcium binds to this protein, so if there is less or more may effect free calcium levels)
  3. Phosphate (levels are closely associated with calcium levels - inversely related)
  4. PTH (if high - could be causing the hypercalcemia)
  5. Vitamin D -
    *25-hydroxyvitamin D3 (inactive form)
    *1,25-dihydroxyvitamin D3 (calcitriol - active form) - this is increased in non-hodgkin lymphoma - may be causing hypercalcemia
  6. Parathyroid hormone related peptide (PHrP)
    -increased in adenocarcinoma or squamous cell cancer - can effect calcium levels
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7
Q

Calcium correction

A

If we only have the total calcium (not ionized), we need to “correct” it
-it needs to be corrected based on albumin

Corrected calcium (mg/dL) = measured total calcium + 0.8 (4 - serum albumin)

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8
Q

What effect can serum pH have on calcium

A

the pH effects the binding of calcium to albumin, and therefore effects the ionized/free calcium level

When pH is low (acidosis) = higher ionized calcium (less binding to albumin)

When pH is high (alkalosis) = lower ionized calcium (more binding to albumin)

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9
Q

How does hypercalcemia present?

A

It is usually asymptomatic

However, if signs/symptoms are present - that means it is SEVERE disease

Pneumonic to remember some symptoms:
Stones, bones, groans, and moans
Stones = renal and pancreatic stones
Bones = bone pain, fractures
Groans = GI pains - constipation, n/v, anorexia/weight loss, peptic ulcer disease
Moans = psychiatric symptoms - malaise, confusion, lethargy

There are also CV symptoms = shortening of QT interval = dysrhythmias

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10
Q

What are the main causes of hypercalcemia (2)

A

hyperparathyroidism and malignancy (multiple myeloma, neoplasm)

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11
Q

Why is it important to recognize/treat hypercalcemia?

A

It can lead to coma and death if severe

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12
Q

Calcium absorption

A

Calcium is primarily absorbed in the small intestine

Only about 10-20% of ingested calcium is absorbed (the rest is used in the skeletal system and other processes of the body that need it)

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13
Q

Normal calcium metabolism (what happens to increase calcium level in the blood?)

A

Calcium is primarily regulated by PTH and Vitamin D

When calcium levels < 10 mg/dl…
The parathyroid gland stimulated release of parathyroid hormone (PTH)

PTH activates l-alpha-hydroxylase - this is an enzyme that converts calcidiol (inactive vitamin D) into calcitriol (active vitamin D)

Active vitamin D…
-stimulates calcium reabsorption (in the distal part of the nephron)
-stimulates phosphorus excretion
-increases osteoclast production (which increases bone resorption and mobilization of calcium from bone into the blood)

We can target different parts of this pathway (which increases calcium level) to treat hypercalcemia!

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14
Q

Incidence of hypercalcemia in malignancy

A

Malignancy accounts for 20-30% of hypercalcemia cases
80% die in the first year of treatment

More common in solid tumors than hematologic
-specifically breast, prostate, lung, and multiple myeloma

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15
Q

What are reasons why cancer can cause hypercalcemia (7)

A
  1. There are skeletal changes - increased bone resorption causes more release of calcium into serum (increased bone resorption decreased bone formation - unbalances osteoclast/osteoblast activity)
  2. Decreased renal function is common in cancer - which causes decreased clearance of calcium (increase in serum)
  3. Immobility - common in cancer patients
  4. Certain medications
  5. tumor secretion of PHrP
  6. Tumor secretion of calcitriol
  7. osteolytic metastases
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16
Q

What is the most common cancer associated cause of hypercalcemia?

A

Tumor secretion of parathyroid hormone related protein (PHrP)

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17
Q

In which cancer types can tumor release of PHrP occur? (5)

A

Lung
Esophagus
Skin
Breast
Kidney

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18
Q

Tumor secretion of parathyroid hormone related protein (humoral hypercalcemia of malignancy) - mechanism of hypercalcemia

A

The tumor secretes PHrP - this is structurally very similar to PTH
It increases bone resorption (increasing calcium release into blood)
Causes distal tubule calcium reabsorption
Inhibits phosphate transport

And it decreases levels of PTH and active Vitamin D

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19
Q

Osteolytic metastases - hypercalcemia mechanism

A

This is when the tumor releases cytokines which stimulate osteoclast production - this stimulates bone resorption and increases calcium levels in the blood

20
Q

In which types of cancers can osteolytic metastases occur? (3)

A

Breast
Multiple myeloma
Hematologic cancers

21
Q

How does tumor production of calcitriol lead to hypercalcemia?

A

Normally, if calcium levels are high, the body would suppress the release of PTH and calcitriol (active vitamin D) - but in this case the tumor is releasing calcitriol - leading to hypercalcemia due to heightened intestinal reabsorption

22
Q

Tumor production of calcitriol is seen most in which 2 cancer types?

A

Lymphoma and myeloma

23
Q

General treatment approach based on severity of hypercalcemia

A

Mild (10-12)
-treatment is usually NOT needed

Moderate (12-14)
-basic treatment + aggressive hydration

Severe (>14)
-aggressive INPATIENT treatment (to monitor closely for severe acute symptoms)

24
Q

Hydration (fluids +/- diuretics)

A

This is the backbone of hypercalcemia therapy - patients are often dehydrated on presentation, we want to volume expand to enhance calcium excretion and prevent renal damage

Hydration is done with IV isotonic fluids - Normal Saline ONLY (LR should NOT be used because it contains calcium)

Caution in patients at risk for fluid overload (oliguria or heart failure) - may need to add loop diuretic here

Loop Diuretics can be added to help with volume control (prevent fluid overload) AND to help promote calcium excretion

25
Q

What should we monitor for with IV hydration/diuretics

A

Potassium and magnesium
(can be affected by fluids and diuretics)

26
Q

Bisphosphonate mechanism

A

Inhibits bone resorbing osteoclasts (inhibiting release of calcium into the blood from bone)

Note - the mechanism is slightly different from Calcitonin, so these agents can and should be used together

27
Q

Which bisphosphonates are used for hypercalcemia? (2)

A

IV formulations…
-Pamidronate IV
-Zoledronic acid IV

28
Q

Bisphosphonate onset/duration

A

These have a longer onset (2-3 days)
But are long acting agents - effect lasts several weeks

29
Q

Bisphosphonate side effects (4)

A

Rebound hypercalcemia
Hypophosphatemia
Osteonecrosis of the jaw
Nephrotoxicity (monitor creatinine and urine output)

30
Q

Calcitonin mechanism

A

Inhibits bone resorbing osteoclasts
And enhances calcium excretion into urine

31
Q

Calcitonin onset/duration/use

A

It has a rapid onset (< 2 hours)
But it is associated with tachyphylaxis (tolerance develops)
- because of this decreased benefit is seen after 2 days of use

So, it is effective to use in the beginning of treatment for some immediate benefit, but not after that

32
Q

Calcitonin ADRs/considerations

A

ADRs: rhinitis, flushing, dizziness, nausea, injection site reaction (SQ injection)

Salmon derived product (consider fish allergy)

33
Q

Corticosteroid mechanism for hypercalcemia treatment

A

Inhibits the l-alpha-hydroxylase enzyme from converting inactive vitamin D to active vitamin D (calcitriol)

Also decreases intestinal calcium absorption

34
Q

Which corticosteroid/administration is used for hypercalcemia?

A

Hydrocortisone IV first for 3-5 days
Then switch to PO prednisone for 7 days

35
Q

Corticosteroid side effects

A

Many ADRs

Immunosuppression - big one to consider, especially in cancer patients that are already at risk for infection for various reasons

Others: hypertension, hyperglycemia, muscle weakness and altered mental status

36
Q

Corticosteroids are the treatment of choice for which cause of hypercalcemia?

A

Tumor production of 1,25-dihydroxyvitamin D (calcitriol)
-which is commonly seen in lymphoma and myeloma

37
Q

Denosumab mechanism

A

Monoclonal antibody that binds to RANKL
Inhibits osteoclast maturation, activation, and function

38
Q

Denosumab administration

A

SQ weekly injections for 4 weeks, then once every 4 weeks until resolution of hypercalcemia

39
Q

Denosumab side effects

A

Arthralgia
Risk of osteonecrosis
Risk of hypocalcemia (leading to renal failure)
Peripheral edema
Fatigue
headache

40
Q

When is denosumab a key addition to therapy? (3)

A

In patients with severe disease (particularly if bone resorption is being driven by cancer metastasis)

If patients have cardiac or renal dysfunction (since this may limit the use of other agents)

Or if refractory to bisphosphonate therapy

41
Q

What are the 2 brands of denosumab, which one is approved or hypercalcemia?

A

Xgeva and Prolia

Xgeva is approved for hypercalcemia of malignancy

Prolia is NOT (approved for osteoporosis/bone loss)

42
Q

Cinacalcet mechanism

A

Downregulates PTH, decreasing serum calcium

43
Q

Cinacalcet is the preferred agent for which patients?

A

Patients on dialysis

44
Q

Cinacalcet side effects

A

Hypotension
N/v/d
headache
myalgia
Increased risk of hypocalcemia (leading to renal failure)

45
Q

What is the last line option for hypercalcemia treatment?

A

Dialysis
-used to remove calcium
-not a great option, usually if used combined with other pharmacologic options

46
Q

Treatment summary for hypercalcemia

A
  1. Normal saline +/- loop diuretics
  2. Bisphosphonates
  3. Calcitonin
  4. Corticosteroids
  5. Denosumab (Xgeva)
  6. Cinacalcet
  7. Dialysis

Hematology/Oncology (17 decks)

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