"Many primary care clinical teams are more tired than usual due to their response to Covid-19 and want longer leave breaks."
North Shore and Waitakere Hospitals had also seen a high demand for services over the last two weeks, a Waitemata DHB spokesperson said.
She said the increased demand was due to population growth. Long-term investment plans were underway to address the issue.
It comes as Newshub tonight reported emergency departments around the country were seeing unprecedented numbers of patients, and Middlemore Hospital was struggling to find beds.
Dr Vanessa Thornton, Emergency Department clinical director at Middlemore Hospital, said ambulances were lining up outside ED on Monday night, which had only happened once before - the previous Monday.
"We had patients supervised by clinicians but obviously it's not the ideal scenario."
She told Newshub it was worrying what the winter months could bring if this issue wasn't addressed.
Sarah Dalton, executive director at senior doctors' union Association of Salaried Medical Specialists (ASMS), told the Herald it was very common for Middlemore to be running at just over 100 per cent capacity.
"It doesn't make it okay ... it is a concern because it is a really important hospital, it's a really needy community and [the DHB] struggles with capacity issues much of the time."
Dalton said when hospitals were running over 100 per cent capacity it meant they didn't have beds available and people end up waiting longer in ED.
"Patients are being put in further danger."
However, Middlemore told the Herald that even when it was experiencing capacity issues it had plans to ensure any patient who required a bed was provided with one.
"We do not turn patients away."
Hospital's advice to patients:
• Only come to the ED for emergencies, including injuries which threaten life or limb.
• You don't have to go to the hospital's ED to get the appropriate treatment. Most times a GP or family doctor can provide medical advice and prescriptions to manage acute injuries and illnesses as well as long-term conditions.
• Alternatively, Accident and Medical clinics provide support for patients who feel unwell outside of regular GP hours or on weekends and public holidays. These clinics provide free or low-cost care for children under 14 years old, adults over 65, and Community Service Card or High User Health Card holders.
• If a person doesn't have a family doctor they can find one on Healthpoint which is an online directory for GPs and also provides information on Accident and Medical clinics.
• Health advice is also available 24 hours a day by calling Healthline on 0800 611 116 with the service providing interpreters for non-English speakers.