QuestionSBA
QuestionChoice
In primary hypoparathyroidism, PTH is low, calcium is low, and phosphate is high. This is because of reduced osteoclastic activity in bone and so reduced serum calcium produced from bone reabsorption. Low PTH would also result in reduced reabsorption of calcium in the distal tubules and collecting ducts (reduces serum calcium), and reduced inhibition of reabsorption of phosphate from tubular fluid (increases serum phosphate)
33234
b
Primary hypoparathyroidism
QuestionChoice
This patient does have iron-deficiency anaemia, although this is very common in patients with cancer. There is no evidence of acute haemorrhage to cause this patient's confusion and a mildly increased urea gives further evidence against having had an upper gastrointestinal haemorrhage. Patients often compensate very well with chronic anaemia and may have few or no symptoms. They may complain of general lethargy and shortness of breath on exertion with haemoglobin (Hb) in the 80s, but without signs of acute haemorrhage, this is unlikely to cause confusion
33237
e
Microcytic iron deficiency anaemia
QuestionChoice
Tumour lysis syndrome (TLS) is a potentially fatal complication from chemotherapy. It is more likely seen in cancers with high cell turnover rates, particularly haematological malignancies, e.g. lymphomas and leukaemias, but other solid tumours have also been associated with TLS. It is caused by tumour cells being lysed during treatment and releasing their contents into the blood, producing similar electrolyte abnormalities as rhabdomyolysis. It results in hyperkalaemia, hyperphosphataemia, hypocalcaemia, and hyperuricaemia (high blood uric acid). The patient has presented with symptoms that could be consistent with TLS, although it has been four weeks since his last cycle of chemotherapy and so this is very unlikely. His blood markers are also not consistent with TLS, and so this would be an unlikely cause for this patient's symptoms
33235
c
Tumour lysis syndrome
QuestionChoice
The patient's symptoms are most likely caused by his hypercalcaemia. It rarely presents with _all_ of "stones, moans, groans, and psychic overtones" and often presents solely as lethargy or confusion. Non-small cell lung cancers often can cause hypercalcaemia due to tumour secretion of parathyroid-related protein (PTHrP). This acts in the same way as parathyroid hormone (PTH), activating parathyroid hormone receptors in tissue which results in increased osteoclastic bone resorption (with or without bone metastases), increased renal tubular absorption of calcium, and decreased reabsorption of phosphate in the kidney. The body's normal homeostatic mechanisms are still intact, and so secretion of PTH from the parathyroid gland is reduced to combat the patient's hypercalcaemia. Alkaline phosphatase is increased because of increased osteoclastic bone resorption. This patient's palpitations and new ECG findings can also be explained by hypercalcaemia. ECG findings found in hypercalcaemia are short QT interval, prolonged PR-interval (1st degree heart block), and Osborn waves.
 

 This patient has likely also developed an acute kidney injury (AKI) secondary to dehydration from hypercalcaemia - driven by forced diuresis and reduced oral intake from nausea/confusion. NB: The patient may not volunteer polyuria unless asked directly. While the patient does have raised urea, likely from pre-renal AKI, this would not usually elicit cognitive dysfunction at this concentration.
 

 This patient does have iron-deficiency anaemia, although this is very common in patients with cancer. There is no evidence of acute haemorrhage to cause this patient's confusion and a mildly increased urea gives further evidence against having had an upper gastrointestinal haemorrhage
33233
a
Hypercalcaemia of Malignancy
QuestionChoice
In primary hypoparathyroidism, PTH is low, calcium is low, and phosphate is high. This is because of reduced osteoclastic activity in bone and so reduced serum calcium produced from bone reabsorption. Low PTH would also result in reduced reabsorption of calcium in the distal tubules and collecting ducts (reduces serum calcium), and reduced inhibition of reabsorption of phosphate from tubular fluid (increases serum phosphate)
33236
d
Uraemia
QuestionComment
A question longer than johnny sins
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User
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Yellow Zebras
QuestionComment
why is PTH low if PTH is being secreted causing high calcium?
24688
QuestionComment
The tumour secretes parathyroid-related protein not PTH. This causes a rise in calcium similar to if there was a rise in PTH. This results in negative feedback on the parathyroid and the body is like, 'hey I don't need to increase calcium' so PTH levels from the parathyroid fall to very low levels.
25674
User
subscriber
Jaundice Tachycardia
QuestionComment
PTHrP =! PTH-> suppressed PTH due to HHM.
25744
User
subscriber
Gas Contusion
User
subscriber
Mitochondria
QuestionComment
A very well-thought out Q testing lots of areas (tough, but not in the normal bull rote learning Quesmed way)
29297
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Inpatient Syndrome
Concept
Chapter
# Summary

Confusion is a common issue in oncology, with diverse causes including metabolic disturbances, infections, and metastatic spread to the brain. It is crucial to identify and treat underlying factors, as confusion can distress patients and families. Delirious patients face higher risks of falls and complications, requiring careful management strategies.


# Differentials of confusion in oncology

Confusion is a common presenting complaint within general medicine and oncology. Confusion seen in the context of a cancer patient alters the likelihood of certain causes of confusion.

There are a diverse range of causes for confusion in oncology patients:

- **Metabolic disturbance** (hypoglycaemia, hypercalcaemia): this may present acutely or subacutely. Patients often have concurrent symptoms such as feeling hungry or shaky for hypoglycaemia and very thirsty or GI upset for hypercalcaemia.
- **Neutropenic sepsis**: this is an oncological emergency and may be difficult to spot, as many usual signs of infection may be absent. In any patient with known or suspected neutropenia presenting with confusion, neutropenic sepsis should be top of the differential list.
- **Infection** (pneumonia, UTI): patients may have localising symptoms of infection. For example, a cough or dysuria. However patients may present atypically so always consider whether sepsis could be causing the confusion, even in the absence of typical signs.
- **Metastatic spread to the brain**: typically, this is subacute onset and associated with headache, visual disturbances and/or focal neurology. The most common cancers to spread to the brain are lung, breast, colorectal, melanoma and renal cell carcinoma. Therefore have a low threshold for suspecting metastases especially in these cancers.
- **Anaemia**: this may be difficult to diagnose clinically, as cancer and its treatment causes fatigue for most patients. A full blood count is a useful investigation to rule out anaemia and neutropenia.
- Other causes of delirium, including **pain, constipation and medications**. It is important to rule out these reversible causes of confusion. This can be elicited in the history and medication review, and treatment can make a significant difference to the patient's mental status and quality of life.

# Management

It is important to recognise and treat the underlying cause of confusion. This can be distressing for the patient and relatives alike.

Patients with delirium (acute confusional state) are at increased risk of falls, increased mortality and morbidity. Environmental modifications can help reduce confusion, as well as optimising reversible factors and falls risk reduction measures. Pharmacological management is reserved for when non-pharmacological measures do not work or when a patient is agitated towards the end of life.

# NICE guidelines

[NICE CKS: Delirium](https://cks.nice.org.uk/topics/delirium/)

# References

[Marie Curie: Delirium in palliative care](https://www.mariecurie.org.uk/professionals/palliative-care-knowledge-zone/symptom-control/delirium)
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Differentials of Confusion in oncology
Topic
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Oncology and Palliative Care
Hypercalcaemia of Malignancy
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Hypercalcaemia of malignancy can cause confusion and lethargy, often due to parathyroid hormone-related peptide secretion from tumours.
A 65-year-old man is brought to A&E with progressive confusion over the past week, lethargy and sleepiness. He is disoriented and reports occasional palpitations. He has a 60-pack-year smoking history and was diagnosed with non-small cell lung cancer nine months ago, and has completed multiple cycles of chemotherapy and radiotherapy, with the last cycle four weeks ago.


He is tachycardic, apyrexial, and has dry mucous membranes. His chest is clear, abdomen is soft and non-tender, with no focal neurology.  


ECG shows new 1st degree heart block; urine dip is clear. Chest X-ray shows a known left hilar mass.



Bloods tests:


|Serum|Result|Reference Range|
|---------------------------|------|-----------------------------|
|Haemoglobin|82|130 - 170 mg/dL|
|White Cell Count|4.1|3.0 - 10.0 x 10⁹ /L|
|Platelets|180|150 - 400 x 10⁹/L|
|Mean Cell Volume|71|80 - 96 fL|
|Urea|10.1|2.5 - 7.8 mmol/L|
|Creatinine|170|60 - 120 µmol/L|
|eGFR|37|≥ 60 mL/min/1.73m<sup>2</sup>|
|Iron|5.6|14 - 31 μmol/L|
|Total Iron Binding Capacity|35|54 - 75 μmol/L|
|Corrected Calcium|3.6|2.2 - 2.6 mmol/L|
|Magnesium|0.65|0.7 - 1.0 mmol/L|
|Phosphate|0.4|0.8 - 1.5|
|Parathyroid Hormone|0.1|1.6 - 8.5 pmol/L|


What is the most likely cause of this patient's symptoms?
a