So you’ve finally got your rota for your hotly anticipated renal rotation… and your first shift is out of hours. But worry not, for this guide will help you to prepare for that dreaded on-call.  

While medical on-calls are usually a medium-to-high, consistent workload, the renal on-call is typically either quite calm or really busy. Your patients are either stable or very, very sick!  

In this article, we will look at the responsibilities of the ‘renal SHO’, how renal patients differ from other medical patients, how to approach renal problems, and hopefully ease your mind about that worrisome renal bleep. This list is not exhaustive, and, as always, if you are unsure about anything, you should always escalate.  

‘Hello, this is Dr so-and-so, renal SHO on call’  

Depending on your hospital renal facilities, you are likely to only hold the renal bleep in F2 or above. The responsibilities of the renal SHO may include:

• Covering a renal ward (deteriorating patients, clerking new patients, basic ward tasks)  
• Covering a renal HDU or high-care area 
• Covering renal patients in other wards  
• Taking renal referrals from A+E or other hospitals (usually only after discussion with the renal registrar/consultant)  
• Receiving (and acting upon) out-of-hours abnormal blood findings from the labs. This may include lab results from GP practices or dialysis units around the area  
• Assisting in emergency renal scenarios (e.g. emergency dialysis)  
• Assisting the renal registrar/consultant in their out-of-hours duties  
• Aiding the medical on-call team  

Your duties (unless you are trained or stipulated to do so), should not consist of:  

• Deciding whether to admit patients into the renal HDU or high care area (usually this would be done with senior doctor input)  
• Performing procedures you are not comfortable with (e.g. dialysis line insertion)  
• Giving specific renal advice outside of your remit as a foundation trainee  
• Doing ‘day team’ tasks that can wait until normal working hours  

Renal Patients

“Renal patients” are in hospital because of one of four things:  

• Deterioration of pre-existing renal disease 
• AKI without previous CKD (see article on AKI)  
• A non-kidney problem that is exacerbated or complicated by their renal problem (e.g. pneumonia on top of chronic fluid overload / pulmonary oedema secondary to CKD)  
• A pathology completely unrelated to their renal disease, but requiring renal input during admission (e.g. road traffic accident in a patient who requires dialysis) 

Though all the above examples could look very different, there are some common lines to think along when you hear that pager buzzing:

1. Renal patients are Vulnerable

Renal patients tend to be more frail and more prone to sudden deterioration than their contemporaries. Studies suggest that poor oral intake, reduced physical activity, a pro-inflammatory state and multiple other causes, make a renal patient far more vulnerable than one would expect for their age. This is always worth considering when hearing the dreaded bleep at 3 am and wondering whether to get a coffee before answering.  

2. Damaged kidneys don’t handle drugs well

Or fluids! Be gentle with both. There are websites such as the ‘renal drug database’ which, according to patient eGFR or dialysis status, can alter drug doses. This is not just of the nephrotoxic medications – any renally excreted drug may need adjustment. Ask your renal team if the hospital has a subscription. Always run renal drug dosing by a pharmacist if you are unsure. 

For IV fluid requirements, be gentle and cautious, especially in dialysis patients. Again, ask your registrar or consultant if you are unsure about fluid resuscitation/balance/maintenance in renal patients. 

3. Renal nurses know what they’re doing

Renal patients in hospitals also tend to be cared for by more experienced nurses, including dialysis nurses, renal nurses and ICU-trained nurses. These guys know what they are talking about, and have more experience with renal patients than you probably do. So, if the dialysis nurse is worried about a patient – you should be too!  

4. Chronic renal patients are on first-name terms with their kidneys

CKD and dialysis patients often have a good idea of their disease and how it is going. Some patients will be able to list off their last 20 creatinine readings or tell you the fluctuations in their dry weights and targets. Some may even have their blood tests linked to their phone! Many renal patients are expert patients, so listen to them!   

Common renal bleep scenarios

Bear in mind that your clinical duties may vary depending on your hospital and renal team, and that these are general guidelines. Your judgement, experience and the specific patient scenario will all be very important in determining how you respond to a bleep.  

‘Hi, this is Mark from the lab, one of your dialysis unit blood has come back with a potassium of 6.9’  

Take down the name and NHS number of the patient. The next thing to do is find where and when this blood was taken. This will determine your response. See if the lab technician can tell you, and DOUBLE CHECK this on your online results database. Always take the full U&E result down and ask the lab if they have any previous values (they may be calling from a lab that you do not have access to). 

Most pre-dialysis blood abnormalities will be fixed or helped by dialysis – notably potassium, urea and creatinine (usually calcium and phosphate too). So it’s important to find out if the blood result is from a patient who receives dialysis, and if so, whether the blood was taken pre or post-dialysis.  

The general rules for each abnormality (always remember to confirm it is a true result!):  

High K+:  

A pre-dialysis hyperkalaemia is unlikely to be relevant (unless very high, if so then good practice to highlight to dialysis unit so the patient can be reviewed promptly in the dialysis clinic). Most dialysis patients’ K+ will rise between dialysis sessions. Hyperkalaemia should resolve after dialysis. Again, good practice would be to ring the dialysis unit to ensure the patient is on or had dialysis without issue. 

Post-dialysis hyperkalaemia is rare, and usually only occurs if dialysis stops prematurely or if there is a problem with the dialysis / dialysis access itself. If present, needs to be treated like hyperkalaemia in a non-renal patient which is a medical emergency. The patient should be called and asked to attend the hospital for review. They may require further dialysis and should be assessed for why they are hyperkalaemic despite having dialysis. 

Renal patients who don’t dialyse should be treated in the same manner as non-renal patients with high potassium. 

Low K+:  

Dialysis patients often get transient hypokalaemia post-dialysis. This does not need treatment unless severely low (discuss with your senior, usually potassium <2.5) or the patient is symptomatic or shows signs of hypokalaemia (ECG changes, weakness, arrhythmias).  

Sodium abnormalities:  

First, repeat the blood test. Sodium abnormalities in renal patients can generally be treated like non-renal patients (see MTB – Hyponatraemia). Sodium abnormalities in dialysis patients can be complicated and you will probably want to discuss these with your senior team, especially if markedly abnormal. 

Calcium abnormalities: 

See generic advice on these links with regards to hypocalcaemia and hypercalcaemia: MTB – Hypocalcaemia. OR MTB – Hypercalcaemia)  

Calcium physiology in renal patients can be difficult to understand. Important to bear in mind the classic low calcium found in CKD and dialysis patients. This is caused by impaired vitamin D production in the failing / failed kidneys, reducing calcium absorption, plus a raised phosphate mopping up what little free calcium is still present. This is treated with a variety of medications, including vitamin D analogues, phosphate binders and oral calcium replacement.  

Let the day team handle chronic hypocalcaemia. Acutely, the first step is to ensure there are no ECG changes caused by low calcium. Recheck the result and send a magnesium. After this, discuss with your senior team as to whether to replace Calcium orally or IV. Remember, IV calcium contains fluid and it may be best to try and replace Calcium orally if you are able to in order to avoid fluid load. In some renal patients, calcium replacement may actually do harm (rhabdomyolysis) so it is always important to check with your senior team first as calcium physiology can become very complicated. 

Hypercalcaemia in renal patients is common and usually iatrogenic (eg. too much oral calcium replacement). Always check for Myeloma and consider Malignancy however if new. If hypercalcaemia doesn’t settle despite stopping oral calcium replacement then need to consider the cause, relaxing fluid restriction / IV fluids and other medicines. 

Low Mg:  

Unlikely to be relevant out of hours unless it is severely low. Ensure Calcium and Potassium are checked too. Treat as you would treat a non-renal patient (i.e. oral Mg salts or IV Mg if life-threatening). 

High Mg:  

Uncommon and unlikely to be relevant out of hours. Stop Mg supplements if currently taking them. 

High creatinine or urea  

If this is not one of “your” renal patients, then you need to tell the doctor on call who is looking after that patient – they’re likely to become a renal patient if nothing is done about it! Unless the patient qualifies for emergency dialysis, you likely won’t need to do much out-of-hours. Their doctor on-call probably will need to start AKI investigations and treatment. If the patient is an outpatient, they should be called to check they are well. In some cases, they may be asked to attend hospital as an emergency if the bloods are bad enough to need immediate management.  

Some hospitals also have dedicated AKI nurses; if they work out of hours, you might want to let them know instead of the on-call doctor.  

Don’t forget – dialysis patients will often have frighteningly high urea and creatinine. Dialysis drops urea and creatinine temporarily, but they inevitably rise again between sessions. Look at the trend. Urea is the problem (uraemia / uraemic symptoms), not creatinine. If the urea and creatinine are within the patient’s normal range, and the patient has no symptoms, it’s likely you won’t have to do anything out of hours. 

As always, exercise clinical judgment and escalate if you’re not sure about anything. 

‘I’ve got a renal patient in A+E, I need you to review them’  

Depending on the remit of on-calls (best to clarify with a talk to the registrar / consultant at the start of the shift), this may not be exclusively your job.   

Get some more information and inform the renal registrar / consultant promptly. Follow their lead as to whether you should go down and clerk the patient or get more information about whether they require renal input or not.  

‘Doctor, I just took this patient off dialysis and they have x symptom’  

Dialysis nurses know the most common dialysis side effects and can usually handle them themselves. As mentioned above, if they’re worried, you probably should be too.  

Bleeding from a fistula post-dialysis is not uncommon.  

If there is heavy bleeding, this is an emergency, put out an emergency call and activate the massive haemorrhage protocol (if there is one in your hospital).  

Prolonged bleeding is also an issue. This is usually caused by:  

• Thin blood (is their anticoagulant dose too high?)  
• High fistula pressure (stenosis, thrombosis)  
• Thin skin over the fistula site or ruptured scabs 

The only things you can do is minimise the bleeding (by applying pressure- at least 20 minutes) and potentially reversing the anticoagulation (though speak to a senior first). If this isn’t working, the worst-case scenario is surgical intervention, for which you will need to speak to the surgeon who deals with fistulas in your hospital. This will usually be a renal transplant surgeon or a vascular surgeon. 

Anything infective sounding (fevers, redness at dialysis line exit site, rigors on dialysis etc) could be a sign of a dialysis line infection. This is very serious and requires:  

              –  Sepsis bloods (including line and peripheral cultures)  

              – Septic screen (for other causes)  

– Broad-spectrum antibiotics as per your trust policy 

              – Symptomatic treatment (though be careful with fluid resuscitation)  

Cardiac symptoms (syncope, dizziness, palpitations, etc) could have many causes in dialysis patients. Too much fluid may have been taken off in dialysis. Patients can have reactions to dialysis fluid or dialysis membrane / kidney. Dialysis patients are also prone to cardiac events (MI, arrhythmia etc).  

If you think it’s just too much fluid taken off on dialysis (this is likely if they are below their dry weight, had a change of dialysis regime, or have features like orthostatic hypotension), start with a small fluid bolus (250ml maximum). If they’re still hooked up to their dialysis machine, give the fluid through this.  

Any concerns of cardiac events need to be treated as you would treat them in a non-renal patient. Chest pain on dialysis is usually a bad thing! – think of cardiac events, review the patient and escalate to your seniors.  

Headache on dialysis is common. Exclude other causes (hypertension, bleeds) and treat with simple analgesia. If recurring, highlight to the patient’s dialysis consultant as dialysis parameters can be adjusted in order to try and combat this. 

Cramping pains in the legs can occur on dialysis, usually, if fluid is being taken off too quickly or if the patient is fluid depleted / dry weight is incorrect. Slow the UF rate (fluid removal rate on dialysis) and offer analgesia. Check their BP, fluid status and dry weight. Dry weight may need adjustment. This isn’t your job out of hours but please highlight it to the dialysis staff / dialysis consultant so this can be reviewed. 

Peritoneal dialysis patients can also have PD-specific issues while on dialysis.  

PD problems are complicated and usually should be escalated to your registrar or consultant. 

Peritoneal dialysis has a risk of infection (PD peritonitis or exit site infection). These require swabs, antibiotics, potentially a sepsis screen and bleeping your registrar / consultant for further advice. In certain circumstances (e.g. fungal peritonitis), it will require emergency removal of the PD catheter.  

Don’t forget that just because a patient is on dialysis, this doesn’t mean the dialysis is the cause of their symptoms, often it isn’t!  

The above is not a full list of dialysis complications. If asked, go and see the patient on dialysis and if unsure escalate to your registrar or consultant. 

‘Hi Doctor, this patient’s AKI is worsening and I think they need dialysis’  

There are only 5 absolute indications for emergency dialysis, which can be remembered by the mnemonic ‘AEIOU’:  

*common dialysable toxins include lithium, aspirin, theophylline along with many others. 

Depending on other aspects of the clinical scenario, a patient may well need dialysis out of hours but not have one of these indications. Try to get to the nitty-gritty of why exactly the HCP on the other end of the line thinks this patient needs dialysis. If they’re that unwell, it may be that they need more than just dialysis – they might need ITU and other organ support too! 

If the cause of the AKI is uncertain, the patient may need a ‘renal screen’- a bunch of diagnostic tests that help determine more unusual causes of AKI. Ask your registrar / consultant what to include if you’re not certain, but this may include:  

1. Bloods: FBC, U+E, VBG, bone profile, LFT, magnesium, CRP, ANCA, AntiGBM, ANA, DSDNA, Complement, CK, HBA1C, Hep B, Hep C, HIV, Myeloma, Immunoglobulins, PTH, Clotting 
2. Urine: urine dip, urine MC+S, urine ACR, bence-jones proteins etc 
3. Imaging: CXR, renal ultrasound etc 

‘Doctor I can’t get this patient’s dialysis access to work!’  

The approach you take is dependent on whether this is haemodialysis or peritoneal dialysis.  

Haemodialysis  

Unless they are having emergency dialysis, this is probably not going to be something you need to (or can) fix overnight. Dialysis nurses have a variety of procedures for tricky dialysis access, and if they weren’t able to fix it, you probably won’t either.  

A fistula usually becomes blocked due to thrombosis / clot. This is diagnosed clinically and with US Doppler and treated in hours with procedures such as ‘Angiojet lysis’ (procedure to declot the fistula).  

A tunnelled or temporary line can also be blocked by a clot. Sometimes the dialysis nurse can fix it using a ‘line lock’ of a fibrinolytic drug (though you might need to prescribe it).  

Out of hours, all you need to do is work out whether they need emergency dialysis or not. Assess the patient, check fluid status, and check potassium. Look at the ‘AEIOU’ indications above, and check if your patient qualifies. If they do, call the renal registrar / consultant urgently as there needs to be a plan to salvage their access ASAP. If this isn’t possible then they may need a temporary dialysis line. Make sure you’re there to assist!  

If they don’t qualify (still speak to your senior for advice), make sure that stays true until the day team arrives. Recheck their electrolytes if required, keep an eye on their GCS and NEWS, etc. Hand them over in the morning for early review. 

Peritoneal dialysis 

Because PD issues can sometimes be simple and fixable, it’s worth considering the below options, even out of hours.  

Sometimes during PD, there is impaired filling of the peritoneal cavity, or impaired drainage. The most common causes are PD catheter malposition and constipation. Ask for an abdominal XR to find the PD catheter position (it should be within the pelvis) and ask the renal registrar / consultant to review the XR with you. 

A malpositioned catheter is often treated with overfilling the peritoneal cavity, but highlight it to your registrar / consultant, and they will make a plan to try and fix it. 

These patients are also at higher risk of constipation, which unfortunately reduces PD efficacy and drainage. Refer to your hospital guidelines on constipation in PD patients (or ask your PD nurses!) and treat ASAP, as otherwise their PD may be compromised.  

Sometimes the PD catheter can become blocked, causing impaired PD. If the AXR doesn’t show PD catheter malposition and the patient is not constipated, this is the next most likely cause. This is treated with a fibrinolytic drug injected into the catheter or PD bags, but ask your renal registrar / consultant for advice and whether this is indicated out-of-hours.  

Conclusion

The renal on-call can be a challenging shift, but it’s full of interesting and essential medicine. Renal Medicine is a speciality based on holistic interpretation and patient-based approaches rather than purely cold hard numbers and facts, and while this can be trickier than more straight-line specialities, it also will allow you to develop your own skills as an artist of medicine, rather than just a scientist.   

Though Renal Medicine is thought of by many junior doctors as a mysterious, incomprehensible field, with a bit of time and experience, you’ll be thanking your stars for your renal on-calls, and for the more well-rounded, nuanced medic they created.  

References and Further Reading

• NICE – AKI

• Clin Kidney J – Frailty

• Dialysable Drugs Mneumonic

• Harrogate Formulary – Hypokalaemia

• Blood Purification Journal – Mg in CKD

• BNF – Mg imbalance

• The Renal Junior Doctor Handbook, version 2, written for Royal Liverpool University Hospitals Foundation Trust  

Written by Dr Sanjana Mathew, FY3

Edited by Dr James Hartley, Renal Registrar ST7